U.S. patent number 10,949,040 [Application Number 16/092,022] was granted by the patent office on 2021-03-16 for pressure sensor constituting plurality of channels, touch input device including same, and pressure detection method in which same is used.
This patent grant is currently assigned to HIDEEP INC.. The grantee listed for this patent is HiDeep Inc.. Invention is credited to Myung Jun Jin, Bon Kee Kim, Hwan Hee Lee, Sang Sic Yoon.
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United States Patent |
10,949,040 |
Lee , et al. |
March 16, 2021 |
Pressure sensor constituting plurality of channels, touch input
device including same, and pressure detection method in which same
is used
Abstract
A touch input device capable of detecting a pressure of a touch
on a touch surface may be provided. The touch input device
includes: a display module; and a pressure sensor which is disposed
at a position where a distance between the pressure sensor and a
reference potential layer is changeable according to the touch on
the touch surface. The distance is changeable according to a
pressure magnitude of the touch. The pressure sensor outputs a
signal including information on a capacitance which is changed
according to the distance. The pressure sensor includes a plurality
of electrodes to form a plurality of channels. The pressure
magnitude of the touch is detected on the basis of a change amount
of the capacitance detected in each of the channels and an SNR
improvement scaling factor assigned to each of the channels.
Inventors: |
Lee; Hwan Hee (Seongnam-si,
KR), Yoon; Sang Sic (Seongnam-si, KR), Kim;
Bon Kee (Seongnam-si, KR), Jin; Myung Jun
(Seongnam-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
HiDeep Inc. |
Seongnam-si |
N/A |
KR |
|
|
Assignee: |
HIDEEP INC. (N/A)
|
Family
ID: |
1000005424922 |
Appl.
No.: |
16/092,022 |
Filed: |
April 8, 2016 |
PCT
Filed: |
April 08, 2016 |
PCT No.: |
PCT/IB2016/051998 |
371(c)(1),(2),(4) Date: |
October 08, 2018 |
PCT
Pub. No.: |
WO2017/175035 |
PCT
Pub. Date: |
October 12, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190114004 A1 |
Apr 18, 2019 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F
3/0446 (20190501); G06F 3/04164 (20190501); G06F
3/0445 (20190501); G06F 3/0418 (20130101); G06F
3/0412 (20130101); G06F 3/04144 (20190501); G06F
2203/04105 (20130101); G06F 3/04182 (20190501) |
Current International
Class: |
G06F
3/044 (20060101); G06F 3/041 (20060101) |
Field of
Search: |
;345/173-179 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2013127690 |
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Jun 2013 |
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JP |
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2013152129 |
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Aug 2013 |
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JP |
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2015-026094 |
|
Feb 2015 |
|
JP |
|
5894699 |
|
Mar 2016 |
|
JP |
|
2016040734 |
|
Mar 2016 |
|
JP |
|
10-2012-0124314 |
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Nov 2012 |
|
KR |
|
10-2014-0017351 |
|
Feb 2014 |
|
KR |
|
10-1583765 |
|
Jan 2016 |
|
KR |
|
10-2016-0015924 |
|
Feb 2016 |
|
KR |
|
Other References
Office Action from corresponding KR Application No. 10-2018-7032450
dated Jan. 20, 2020. cited by applicant .
International Search Report for corresponding Application No.
PCT/IB2016/051998, dated Jul. 19, 2016. WO. cited by
applicant.
|
Primary Examiner: Chang; Kent W
Assistant Examiner: Shah; Sujit
Attorney, Agent or Firm: The Belles Group, P.C.
Claims
The invention claimed is:
1. A touch input device capable of detecting a pressure of a touch
on a touch surface, the touch input device comprising: a display
module; and a pressure sensor which is disposed at a position where
a distance between the pressure sensor and a reference potential
layer is changeable according to the touch on the touch surface,
wherein the distance is changeable according to a pressure
magnitude of the touch, wherein the pressure sensor outputs a
signal comprising information on a capacitance which is changed
according to the distance, wherein the pressure sensor comprises a
plurality of electrodes to form a plurality of channels, wherein
the pressure magnitude of the touch is detected on the basis of a
change amount of the capacitance detected in each of the channels
and an SNR improvement scaling factor assigned to each of the
channels, wherein the SNR improvement scaling factor is calculated
based on a touch position of the touch, wherein the SNR improvement
scaling factor comprises a first SNR improvement scaling factor and
a second SNR improvement scaling factor, wherein the first SNR
improvement scaling factor is assigned to the channel located
within a predetermined distance from the touch position, and the
second SNR improvement scaling factor is assigned to the remaining
channels, and wherein the first SNR improvement scaling factor is
different from the second SNR improvement scaling factor.
2. The touch input device of claim 1, wherein the first SNR
improvement scaling factor is assigned to N number of the channels
which are the closest to the touch position, and the second SNR
improvement scaling factor of 0 is assigned to the remaining
channels, and wherein the first SNR improvement scaling factor is
1, and wherein the second SNR improvement scaling factor is 0.
3. The touch input device of claim 1, wherein the first SNR
improvement scaling factor is 1, and wherein the second SNR
improvement scaling factor is 0.
4. The touch input device of claim 1, wherein the SNR improvement
scaling factor which is assigned to each of the channels is
calculated based on a distance between the touch position and each
of the channels, and wherein the distance between the touch
position and each of the channels is inversely proportional to the
SNR improvement scaling factor which is assigned to each of the
channels.
5. The touch input device of claim 1, wherein the magnitude of the
touch pressure is detected based on a sum of values obtained by
multiplying the change amounts of the capacitances detected in the
respective channels and the SNR improvement scaling factors
assigned to the respective channels.
6. The touch input device of claim 1, wherein the pressure
magnitude of the touch is detected based on a sum of values
obtained by multiplying the change amount of the capacitance
detected in each of the channels, a sensitivity correction scaling
factor assigned previously to each of the channels, and the SNR
improvement sealing factor assigned previously to each of the
channels, and wherein the sensitivity correction scaling factor
assigned to the channel corresponding to a central portion of the
display module is smaller than the sensitivity correction scaling
factor assigned to the channel corresponding, to an edge of the
display module.
7. The touch input device of claim 1, wherein a volume change
amount of the touch input device is estimated based on the change
amount of the capacitance detected in each of the channels, wherein
the pressure magnitude of the touch is detected based on the
estimated volume change amount and the SNR improvement scaling
factor assigned to each of the channels, wherein the pressure
magnitude of the touch is detected based on the estimated volume
change amount, the SNR improvement scaling factor assigned to each
of the channels, and a reference value corresponding to a
previously stored predetermined touch position, and wherein the
volume change amount of the touch input device is estimated by
calculating a distance change corresponding to each of the channels
from the change amount of the capacitance detected in each of the
channels.
8. The touch input device of claim 1, further comprising a
substrate under the display module, wherein the pressure sensor is
attached to the substrate or the display module, wherein the
reference potential layer is the substrate or the display module,
or the reference potential layer is disposed within the display
module.
9. The touch input device of claim 1, wherein the display module
comprises: a display panel; and a backlight unit which is disposed
under the display panel and comprises a reflective sheet and a
cover, wherein the pressure sensor is attached to the cover,
between the reflective sheet and the cover, wherein the reference
potential layer is located within the display panel, and wherein
the reference potential layer is a common, electrodes within the
display panel.
10. A method for detecting a pressure magnitude of, a touch by
using a plurality of channels in a touch input device which
comprises a display module and constitutes the plurality of
channels for detecting the pressure, the method comprising
detecting the pressure magnitude the touch on the basis of a change
amount of capacitances detected in the respective channels and an
SNR improvement scaling factor assigned to each of the channels,
wherein the SNR improvement scaling factor is calculated based on a
touch position of the touch, wherein the SNR improvement scaling
factor comprises a first SNR improvement scaling factor and a
second SNR, improvement scaling factor, wherein the first SNR
improvement scaling factor is assigned to the channel located
within a predetermined distance from the touch position, and the
second SNR improvement scaling factor is assigned to the remaining
channels, and wherein the first SNR improvement scaling factor is
different from the second SNR improvement scaling factor.
11. The method of claim 10, wherein the detecting the pressure
magnitude of the touch is detecting the pressure magnitude of the
touch on the basis of a sum of values obtained by multiplying a
change amount of a capacitance detected in each of the channels, a
sensitivity correction scaling factor assigned previously to each
of the channels, and an SNR improvement scaling factor assigned
previously to each of the channels, and wherein the sensitivity
correction scaling factor assigned to the channel corresponding to
a central portion of the display module is smaller than the
sensitivity correction scaling factor assigned to the channel
corresponding to an edge of the display module.
12. The method of claim 10, wherein the detecting the pressure
magnitude of the touch is: estimating a volume change amount of the
touch input device on the basis of a change amount of a capacitance
detected in each of the channels; detecting the pressure magnitude
of the touch on the basis of the estimated volume change amount and
an SNR improvement scaling factor assigned to each of the channels;
detecting the pressure magnitude of the touch on the basis of the
estimated volume change amount, the SNR improvement scaling factor
assigned to each of the channels, and a reference value
corresponding to a previously stored predetermined touch position,
and estimating a volume change amount of the touch input device is
estimating the volume change amount of the touch input device by
calculating a distance change corresponding to each of the channels
from the change amount of the capacitance detected in each of the
channels.
13. The method of claim 10, wherein the first SNR improvement
scaling factor is assigned to N number of the channels which are
the closest to the touch position, and the second SNR improvement
scaling factor is assigned to the remaining channels, and wherein
the first SNR improvement scaling factor is 1, and wherein the
second SNR improvement scaling factor is 0.
14. The method of claim 10, wherein the first SNR improvement
scaling factor is 1, and wherein the second SNR improvement scaling
factor is 0.
15. The method of claim 10, wherein the SNR improvement scaling
factor which is assigned to each of the channels is calculated
based on a distance between the touch position and each of the
channels, and wherein the distance between the touch position and
each of the channels is inversely proportional to the SNR
improvement scaling factor which is assigned to each of the
channels.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
The present application is a U.S. national stage application under
35 U.S.C. .sctn. 371 of PCT Application No. PCT/IB2016/051998,
filed Apr. 8, 2016, the disclosure of which is incorporated herein
by reference in its entirety.
TECHNICAL FIELD
The present disclosure relates to a pressure sensor forming a
plurality of channels for pressure detection and a touch input
device including the same, and more particularly to a pressure
sensor which is applied to a touch input device configured to
detect a touch position and forms a plurality of channels for
detecting a touch pressure, the touch input device including the
same, and a pressure detection method using the same.
BACKGROUND ART
Various kinds of input devices are being used to operate a
computing system. For example, the input device includes a button,
key, joystick and touch screen. Since the touch screen is easy and
simple to operate, the touch screen is increasingly being used to
operate the computing system.
The touch screen may constitute a touch surface of a touch input
device including a touch sensor panel which may be a transparent
panel including a touch-sensitive surface. The touch sensor panel
is attached to the front side of a display screen, and then the
touch-sensitive surface may cover the visible side of the display
screen. The touch screen allows a user to operate the computing
system by simply touching the touch screen by a finger, etc.
Generally, the computing system recognizes the touch and a position
of the touch on the touch screen and analyzes the touch, and thus,
performs operations in accordance with the analysis.
Here, there is a demand for a touch input device capable of
detecting not only the touch position according to the touch on the
touch screen but a pressure magnitude of the touch.
DISCLOSURE
Technical Problem
The object of the present invention is to provide a pressure sensor
forming a plurality of channels for pressure detection, a touch
input device including the same, and a pressure detection method
using the same.
Technical Solution
One embodiment is a touch input device capable of detecting a
pressure of a touch on a touch surface. The touch input device
includes: a display module; and a pressure sensor which is disposed
at a position where a distance between the pressure sensor and a
reference potential layer is changeable according to the touch on
the touch surface. The distance is changeable according to a
pressure magnitude of the touch. The pressure sensor outputs a
signal including information on a capacitance which is changed
according to the distance. The pressure sensor includes a plurality
of electrodes to form a plurality of channels. The pressure
magnitude of the touch is detected on the basis of a change amount
of the capacitance detected in each of the channels and an SNR
improvement scaling factor assigned to each of the channels.
Advantageous Effects
According to the embodiment of the present invention, it is
possible to provide a pressure sensor forming a plurality of
channels for pressure detection, a touch input device including the
same, and a pressure detection method using the same.
In addition, according to the embodiment of the present invention,
it is possible to provide the pressure sensor which has a
high-pressure detection accuracy of the touch and forms a plurality
of channels, and the touch input device including the pressure
sensor.
DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic view of a configuration of a capacitance type
touch sensor panel and the operation thereof;
FIGS. 2a to 2e are conceptual views showing a relative position of
the touch sensor panel with respect to a display panel in a touch
input device according to the embodiment;
FIGS. 3a to 3h are cross sectional views of an exemplary pressure
sensor including a pressure electrode according to the embodiment
of the present invention;
FIG. 3i is a view showing a capacitance change amount according to
a distance change between an electrode layer and a reference
potential layer according to the embodiment of the present
invention;
FIG. 4a is a cross sectional view of the touch input device of a
first example, to which the pressure sensor and pressure detection
module according to the embodiment of the present invention can be
applied;
FIG. 4b shows an optical layer of a backlight unit in the touch
input device according to the embodiment;
FIG. 4c is a cross sectional view of the touch input device of a
second example, to which the pressure sensor and pressure detection
module according to the embodiment of the present invention can be
applied;
FIGS. 5a and 5b show a relative distance between the pressure
sensor and the reference potential layer of the first example
included in the touch input device and show a pressure is applied
to the touch input device;
FIGS. 5c and 5d show a relative distance between the pressure
sensor and the reference potential layer of the second example
included in the touch input device and show a pressure is applied
to the touch input device;
FIG. 5e shows the arrangement of pressure sensors of a third
example, which is included in the touch input device;
FIG. 6a is a cross sectional view showing a portion of the touch
input device to which the pressure sensor has been attached
according to a first method;
FIG. 6b is a plan view of the pressure sensor to be attached to the
touch input device in accordance with the first method;
FIG. 6c is a cross sectional view showing a portion of the touch
input device to which the pressure sensor has been attached
according to a second method;
FIGS. 7a to 7e show pressure electrode patterns included in the
pressure sensor for pressure detection according to the embodiment
of the present invention;
FIGS. 8a and 8b show a relation between a magnitude of a touch
pressure and a saturated area in the touch input device to which
the pressure sensor has been applied according to the embodiment of
the present invention;
FIGS. 9a to 9d show cross sections of the pressure sensor according
to the embodiment of the present invention;
FIGS. 10a and 10b show an attachment method of the pressure sensor
according the embodiment of the present invention;
FIGS. 11a to 11c show how the pressure sensor is connected to a
touch sensing circuit in accordance with the embodiment of the
present invention;
FIGS. 12a to 12d show that the pressure sensor according to the
embodiment of the present invention includes a plurality of
channels;
FIGS. 13a to 13c show forms of a first electrode and a second
electrode included in the pressure sensor according to the
embodiment of the present invention;
FIG. 13d shows the form of the first electrode included in the
pressure sensor according to the embodiment of the present
invention;
FIG. 14a is a view showing that a pressure is applied to a
predetermined position in the pressure sensor shown in FIG.
13d;
FIG. 14b is a cross sectional view showing a form in which the
touch input device is bent when the touch pressure is applied to a
touch surface corresponding to a position "A" of FIG. 14a;
FIG. 14c is a cross sectional view showing a form in which the
touch input device is bent when the touch pressure is applied to a
touch surface corresponding to a position "C" of FIG. 14a;
FIG. 15 is a view showing a scaling factor assigned to each first
electrode in the pressure sensor shown in FIG. 13d;
FIG. 16a is a graph for describing, when the pressure is applied to
the position shown in FIG. 14a, a relation between a volume change
amount of the touch input device and a magnitude of the applied
pressure;
FIG. 16b is a cross sectional view showing the volume change amount
of the touch input device shown in FIG. 14b;
FIG. 16c is a cross sectional view showing the volume change amount
of the touch input device shown in FIG. 14c;
FIG. 17a is a partial perspective view for describing a form in
which the touch input device is deformed when the pressure is
applied to the touch input device;
FIG. 17b is a view for describing the estimation of the volume
change amount of the touch input device when the pressure is
applied to the touch input device;
FIG. 17c is a cross sectional view of FIG. 17b;
FIG. 18a shows an equivalent circuit of a device for sensing a
pressure capacitance of the pressure sensor having the forms shown
in FIGS. 13a to 13c;
FIG. 18b shows an equivalent circuit of a device for sensing the
pressure capacitance of the pressure sensor shown in FIG. 13d;
FIG. 19a is a view for describing a case where a pressure is
applied to a position "D" in the pressure sensor shown in FIG.
14a;
FIG. 19b is a graph for describing the calculation of a pressure
value when the pressure is applied to the position "D" shown in
FIG. 19a;
FIGS. 20a to 20c are flowcharts for describing examples of a method
for detecting the magnitude of the touch pressure by using a
plurality of channels in the touch input device according to the
embodiment of the present invention;
FIG. 21a is a graph showing an amplitude of a signal including
information on the capacitance detected in the channel
corresponding to the position "a" of FIG. 17c;
FIG. 21b is a graph showing an amplitude of a signal including
information on the capacitance detected in the channel
corresponding to the position "b" of FIG. 17c;
FIGS. 22a and 22b are views for describing an SNR improvement
scaling factor which is assigned to each channel when a pressure is
applied to a position "P"; and
FIG. 22c is a view showing capacitance change amounts detected in
the respective channels when the pressure is applied to the
position "P".
MODE FOR INVENTION
The following detailed description of the present invention shows a
specified embodiment of the present invention and will be provided
with reference to the accompanying drawings. The embodiment will be
described in enough detail that those skilled in the art are able
to embody the present invention. It should be understood that
various embodiments of the present invention are different from
each other and need not be mutually exclusive. Similar reference
numerals in the drawings designate the same or similar functions in
many aspects.
Hereinafter, a pressure sensor for pressure detection and a touch
input device to which a pressure detection module including the
pressure sensor according to an embodiment of the present invention
can be applied will be described with reference to the accompanying
drawings. Hereinafter, while a capacitance type touch sensor panel
100 is exemplified below, the touch sensor panel 100 capable of
detecting a touch position in any manner may be applied.
FIG. 1 is a schematic view of a configuration of the capacitance
type touch sensor panel 100 which is included in the touch input
device to which a pressure sensor 440 and the pressure detection
module including the pressure sensor 440 according to the
embodiment of the present invention can be applied, and the
operation of the touch sensor panel. Referring to FIG. 1, the touch
sensor panel 100 may include a plurality of drive electrodes TX1 to
TXn and a plurality of receiving electrodes RX1 to RXm, and may
include a drive unit 120 which applies a driving signal to the
plurality of drive electrodes TX1 to TXn for the purpose of the
operation of the touch sensor panel 100, and a sensing unit 110
which detects whether or not the touch occurs and/or the touch
position by receiving a sensing signal including information on the
capacitance change amount changing according to the touch on the
touch surface of the touch sensor panel 100.
As shown in FIG. 1, the touch sensor panel 100 may include the
plurality of drive electrodes TX1 to TXn and the plurality of
receiving electrodes RX1 to RXm. While FIG. 1 shows that the
plurality of drive electrodes TX1 to TXn and the plurality of
receiving electrodes RX1 to RXm of the touch sensor panel 100 form
an orthogonal array, the present invention is not limited to this.
The plurality of drive electrodes TX1 to TXn and the plurality of
receiving electrodes RX1 to RXm has an array of arbitrary
dimension, for example, a diagonal array, a concentric array, a
3-dimensional random array, etc., and an array obtained by the
application of them. Here, "n" and "m" are positive integers and
may be the same as each other or may have different values. The
magnitude of the value may be changed depending on the
embodiment.
As shown in FIG. 1, the plurality of drive electrodes TX1 to TXn
and the plurality of receiving electrodes RX1 to RXm may be
arranged to cross each other. The drive electrode TX may include
the plurality of drive electrodes TX1 to TXn extending in a first
axial direction. The receiving electrode RX may include the
plurality of receiving electrodes RX1 to RXm extending in a second
axial direction crossing the first axial direction.
In the touch sensor panel 100 according to the embodiment of the
present invention, the plurality of drive electrodes TX1 to TXn and
the plurality of receiving electrodes RX1 to RXm may be formed in
the same layer. For example, the plurality of drive electrodes TX1
to TXn and the plurality of receiving electrodes RX1 to RXm may be
formed on the same side of an insulation layer (not shown). Also,
the plurality of drive electrodes TX1 to TXn and the plurality of
receiving electrodes RX1 to RXm may be formed in the different
layers. For example, the plurality of drive electrodes TX1 to TXn
and the plurality of receiving electrodes RX1 to RXm may be formed
on both sides of one insulation layer (not shown) respectively, or
the plurality of drive electrodes TX1 to TXn may be formed on a
side of a first insulation layer (not shown) and the plurality of
receiving electrodes RX1 to RXm may be formed on a side of a second
insulation layer (not shown) different from the first insulation
layer.
The plurality of drive electrodes TX1 to TXn and the plurality of
receiving electrodes RX1 to RXm may be made of a transparent
conductive material (for example, indium tin oxide (ITO) or
antimony tin oxide (ATO) which is made of tin oxide (SnO.sub.2),
and indium oxide (In.sub.2O.sub.3), etc.), or the like. However,
this is only an example. The drive electrode TX and the receiving
electrode RX may be also made of another transparent conductive
material or an opaque conductive material. For instance, the drive
electrode TX and the receiving electrode RX may be formed to
include at least any one of silver ink, copper or carbon nanotube
(CNT). Also, the drive electrode TX and the receiving electrode RX
may be made of metal mesh or nano silver.
The drive unit 120 according to the embodiment of the present
invention may apply a driving signal to the drive electrodes TX1 to
TXn. In the embodiment of the present invention, one driving signal
may be sequentially applied at a time to the first drive electrode
TX1 to the n-th drive electrode TXn. The driving signal may be
applied again repeatedly. This is only an example. The driving
signal may be applied to the plurality of drive electrodes at the
same time in accordance with the embodiment.
Through the receiving electrodes RX1 to RXm, the sensing unit 110
receives the sensing signal including information on a capacitance
(Cm) 101 generated between the receiving electrodes RX1 to RXm and
the drive electrodes TX1 to TXn to which the driving signal has
been applied, thereby detecting whether or not the touch has
occurred and where the touch has occurred. For example, the sensing
signal may be a signal coupled by the capacitance (CM) 101
generated between the receiving electrode RX and the drive
electrode TX to which the driving signal has been applied. As such,
the process of sensing the driving signal applied from the first
drive electrode TX1 to the n-th drive electrode TXn through the
receiving electrodes RX1 to RXm can be referred to as a process of
scanning the touch sensor panel 100.
For example, the sensing unit 110 may include a receiver (not
shown) which is connected to each of the receiving electrodes RX1
to RXm through a switch. The switch becomes the on-state in a time
interval during which the signal of the corresponding receiving
electrode RX is sensed, thereby allowing the receiver to sense the
sensing signal from the receiving electrode RX. The receiver may
include an amplifier (not shown) and a feedback capacitor coupled
between the negative (-) input terminal of the amplifier and the
output terminal of the amplifier, i.e., coupled to a feedback path.
Here, the positive (+) input terminal of the amplifier may be
connected to the ground or a reference voltage. Also, the receiver
may further include a reset switch which is connected in parallel
with the feedback capacitor. The reset switch may reset the
conversion from current to voltage that is performed by the
receiver. The negative input terminal of the amplifier is connected
to the corresponding receiving electrode RX and receives and
integrates a current signal including information on the
capacitance (CM) 101, and then converts the integrated current
signal into voltage. The sensing unit 110 may further include an
analog-digital converter (ADC) (not shown) which converts the
integrated data by the receiver into digital data. Later, the
digital data may be input to a processor (not shown) and processed
to obtain information on the touch on the touch sensor panel 100.
The sensing unit 110 may include the ADC and processor as well as
the receiver.
A controller 130 may perform a function of controlling the
operations of the drive unit 120 and the sensing unit 110. For
example, the controller 130 generates and transmits a drive control
signal to the drive unit 200, so that the driving signal can be
applied to a predetermined drive electrode TX1 at a predetermined
time. Also, the controller 130 generates and transmits the drive
control signal to the sensing unit 110, so that the sensing unit
110 may receive the sensing signal from the predetermined receiving
electrode RX at a predetermined time and perform a predetermined
function.
In FIG. 1, the drive unit 120 and the sensing unit 110 may
constitute a touch detection device (not shown) capable of
detecting whether the touch has occurred on the touch sensor panel
100 according to the embodiment of the present invention or not
and/or where the touch has occurred. The touch detection device
according to the embodiment of the present invention may further
include the controller 130. The touch detection device according to
the embodiment of the present invention may be integrated and
implemented on a touch sensing integrated circuit (IC, not shown)
in a touch input device 1000 including the touch sensor panel 100.
The drive electrode TX and the receiving electrode RX included in
the touch sensor panel 100 may be connected to the drive unit 120
and the sensing unit 110 included in the touch sensing IC through,
for example, a conductive trace and/or a conductive pattern printed
on a circuit board, or the like. The touch sensing IC may be
located on a circuit board on which the conductive pattern has been
printed. According to the embodiment, the touch sensing IC may be
mounted on a main board for operation of the touch input device
1000.
As described above, a capacitance (C) with a predetermined value is
generated at each crossing of the drive electrode TX and the
receiving electrode RX. When an object like a finger approaches
close to the touch sensor panel 100, the value of the capacitance
may be changed. In FIG. 1, the capacitance may represent a mutual
capacitance (Cm). The sensing unit 110 senses such electrical
characteristics, thereby being able to sense whether the touch has
occurred on the touch sensor panel 100 or not and where the touch
has occurred. For example, the sensing unit 110 is able to sense
whether the touch has occurred on the surface of the touch sensor
panel 100 comprised of a two-dimensional plane consisting of a
first axis and a second axis.
More specifically, when the touch occurs on the touch sensor panel
100, the drive electrode TX to which the driving signal has been
applied is detected, so that the position of the second axial
direction of the touch can be detected. Likewise, when the touch
occurs on the touch sensor panel 100, the capacitance change is
detected from the reception signal received through the receiving
electrode RX, so that the position of the first axial direction of
the touch can be detected.
The mutual capacitance type touch sensor panel as the touch sensor
panel 100 has been described in detail in the foregoing. However,
in the touch input device 1000 according to the embodiment of the
present invention, the touch sensor panel 100 for detecting whether
or not the touch has occurred and where the touch has occurred may
be implemented by using not only the above-described method but
also any touch sensing method like a self-capacitance type method,
a surface capacitance type method, a projected capacitance type
method, a resistance film method, a surface acoustic wave (SAW)
method, an infrared method, an optical imaging method, a dispersive
signal technology, and an acoustic pulse recognition method,
etc.
Hereinafter, a component corresponding to the drive electrode TX
and the receiving electrode RX for detecting whether or not the
touch has occurred and/or the touch position can be referred to as
a touch sensor.
In the pressure sensor and the touch input device 1000 to which the
pressure detection module including the pressure sensor can be
applied according to the embodiment of the present invention, the
touch sensor panel 100 may be positioned outside or inside a
display panel 200A. The display panel 200A of the touch input
device 1000 according to the embodiment of the present invention
may be a display panel included in a liquid crystal display (LCD),
a plasma display panel (PDP), an organic light emitting diode
(OLED), etc. Accordingly, a user may perform the input operation by
touching the touch surface while visually identifying an image
displayed on the display panel. Here, the display panel 200A may
include a control circuit which receives an input from an
application processor (AP) or a central processing unit (CPU) on a
main board for the operation of the touch input device 1000 and
displays the contents that the user wants on the display panel.
Here, the control circuit for the operation of the display panel
200A may be mounted on a second printed circuit board (hereafter,
referred to as a second PCB) (210) in FIGS. 10a to 12c. Here, the
control circuit for the operation of the display panel 200A may
include a display panel control IC, a graphic controller IC, and a
circuit required to operate other display panels 200A.
FIGS. 2a to 2e are conceptual views showing a relative position of
the touch sensor panel 100 with respect to the display panel 200A
in the touch input device to which the pressure sensor 440
according to the embodiment can be applied. First, the relative
position of the touch sensor panel 100 with respect to the display
panel 200A using an LCD panel will be described with reference to
FIGS. 2a to 2c.
As shown in FIGS. 2a to 2c, the LCD panel may include a liquid
crystal layer 250 including a liquid crystal cell, a first
substrate 261 and a second substrate 262 which are disposed on both
sides of the liquid crystal layer 250 and include electrodes, a
first polarizer layer 271 formed on a side of the first substrate
261 in a direction facing the liquid crystal layer 250, and a
second polarizer layer 272 formed on a side of the second substrate
262 in the direction facing the liquid crystal layer 250. Here, the
first substrate 261 may be color filter glass, and the second
substrate 262 may be TFT glass. Also, the first substrate 261
and/or the second substrate 262 may be a plastic substrate.
It is clear to those skilled in the art that the LCD panel may
further include other configurations for the purpose of performing
the displaying function and may be transformed.
FIG. 2a shows that the touch sensor panel 100 of the touch input
device 1000 is disposed outside the display panel 200A. The touch
surface of the touch input device 1000 may be the surface of the
touch sensor panel 100. In FIG. 2a, the top surface of the touch
sensor panel 100 is able to function as the touch surface. Also,
according to the embodiment, the touch surface of the touch input
device 1000 may be the outer surface of the display panel 200A. In
FIG. 2a, the bottom surface of the second polarizer layer 272 of
the display panel 200A is able to function as the touch surface.
Here, in order to protect the display panel 200A, the bottom
surface of the display panel 200A may be covered with a cover layer
(not shown) like glass.
FIGS. 2b and 2c show that the touch sensor panel 100 of the touch
input device 1000 is disposed inside the display panel 200A. Here,
in FIG. 2b, the touch sensor panel 100 for detecting the touch
position is disposed between the first substrate 261 and the first
polarizer layer 271. Here, the touch surface of the touch input
device 1000 is the outer surface of the display panel 200A. The top
surface or bottom surface of the display panel 200A in FIG. 2b may
be the touch surface. FIG. 2c shows that the touch sensor panel 100
for detecting the touch position is included in the liquid crystal
layer 250, that is to say, the touch sensor panel 100 is disposed
between the first substrate 261 and the second substrate 262. Here,
the touch surface of the touch input device 1000 is the outer
surface of the display panel 200A. The top surface or bottom
surface of the display panel 200A in FIG. 2c may be the touch
surface. In FIGS. 2b and 2c, the top surface or bottom surface of
the display panel 200A, which can be the touch surface, may be
covered with a cover layer (not shown) like glass.
Next, a relative position of the touch sensor panel 100 with
respect to the display panel 200A using an OLED panel will be
described with reference to FIGS. 2d and 2e. In FIG. 2d, the touch
sensor panel 100 is positioned between a polarizer layer 282 and a
first substrate 281. In FIG. 2e, the touch sensor panel 100 is
positioned between an organic material layer 280 and a second
substrate 283. Also, the touch sensor panel 100 is positioned
between the first substrate 281 and the organic material layer
280.
Here, the first substrate 281 may be made of encapsulation glass.
The second substrate 283 may be made of TFT glass. Also, the first
substrate 281 and/or the second substrate 283 may be plastic
substrates. Since the touch sensing has been described above, the
other configurations only will be briefly described.
The OLED panel is a self-light emitting display panel which uses a
principle where, when current flows through a fluorescent or
phosphorescent organic thin film and then electrons and electron
holes are combined in the organic material layer, so that light is
generated. The organic matter constituting the light emitting layer
determines the color of the light.
Specifically, the OLED uses a principle in which when electricity
flows and an organic matter is applied on glass or plastic, the
organic matter emits light. That is, the principle is that electron
holes and electrons are injected into the anode and cathode of the
organic matter respectively and are recombined in the light
emitting layer, so that a high energy exciton is generated and the
exciton releases the energy while falling down to a low energy
state and then light with a particular wavelength is generated.
Here, the color of the light is changed according to the organic
matter of the light emitting layer.
The OLED includes a line-driven passive-matrix organic
light-emitting diode (PM-OLED) and an individual driven
active-matrix organic light-emitting diode (AM-OLED) in accordance
with the operating characteristics of a pixel constituting a pixel
matrix. None of them require a backlight. Therefore, the OLED
enables a very thin display module to be implemented, has a
constant contrast ratio according to an angle and obtains a good
color reproductivity depending on a temperature. Also, it is very
economical in that non-driven pixel does not consume power.
In terms of operation, the PM-OLED emits light only during a
scanning time at a high current, and the AM-OLED maintains a light
emitting state only during a frame time at a low current.
Therefore, the AM-OLED has a resolution higher than that of the
PM-OLED and is advantageous for driving a large area display panel
and consumes low power. Also, a thin film transistor (TFT) is
embedded in the AM-OLED, and thus, each component can be
individually controlled, so that it is easy to implement a delicate
screen.
As shown in FIGS. 2d and 2e, basically, the OLED (particularly,
AM-OLED) panel includes the polarizer layer 282, the first
substrate 281, the organic layer 280, and the second substrate 283.
Here, the first substrate 281 may be made of encapsulation glass.
The second substrate 283 may be made of TFT glass. However, they
are not limited to this. The first substrate 281 and/or the second
substrate 283 may be plastic substrates.
Also, the organic layer 280 may include a hole injection layer
(HIL), a hole transport layer (HTL), an emission material layer
(EML), an electron transport layer (ETL), and an electron injection
layer (EIL).
Briefly describing each of the layers, HIL injects electron holes
and is made of a material such as CuPc, etc. HTL functions to move
the injected electron holes and mainly is made of a material having
a good hole mobility. Arylamine, TPD, and the like may be used as
the HTL. The EIL and ETL inject and transport electrons. The
injected electrons and electron holes are combined in the EML and
emit light. The EML represents the color of the emitted light and
is composed of a host determining the lifespan of the organic
matter and an impurity (dopant) determining the color sense and
efficiency. This just describes the basic structure of the organic
layer 280 include in the OLED panel. The present invention is not
limited to the layer structure or material, etc., of the organic
layer 280.
The organic layer 280 is inserted between an anode (not shown) and
a cathode (not shown). When the TFT becomes an on-state, a driving
current is applied to the anode and the electron holes are
injected, and the electrons are injected to the cathode. Then, the
electron holes and electrons move to the organic layer 280 and emit
the light.
Also, according to the embodiment, at least a portion of the touch
sensor may be disposed within the display panel 200A and at least
the remaining portion of the touch sensor may be disposed outside
the display panel 200A. For example, any one of the drive electrode
TX and the receiving electrode RX which constitute the touch sensor
panel 100 may be disposed outside the display panel 200A and the
other may be disposed within the display panel 200A. When the touch
sensor is disposed within the display panel 200A, an electrode for
the operation of the touch sensor may be further added. In
addition, various components and/or electrodes disposed within the
display panel 200A can be also used as the touch sensor for touch
sensing.
Also, according to the embodiment, at least a portion of the touch
sensor may be disposed between the first substrate 261 and 281 and
the second substrate 262 and 283 and at least the remaining portion
of the touch sensor may be disposed on the first substrate 261 and
281. For example, any one of the drive electrode TX and the
receiving electrode RX which constitute the touch sensor panel 100
may be disposed on the first substrate 261 and 281 and the other
may be disposed between the first substrate 261 and 281 and the
second substrate 262 and 283. Here, likewise, when the touch sensor
is disposed between the first substrate 261 and 281 and the second
substrate 262 and 283, an electrode for the operation of the touch
sensor may be further added. In addition, various components and/or
electrodes disposed between the first substrate 261 and 281 and the
second substrate 262 and 283 can be also used as the touch sensor
for touch sensing.
The second substrate 262 and 283 may be comprised of various layers
including a data line a gate line, TFT, a common electrode, and a
pixel electrode, etc. Specifically, when the display panel 200A is
the LCD panel, these electrical components may operate in such a
manner as to generate a controlled electric field and orient liquid
crystals located in the liquid crystal layer 250. Any one of the
data line, the gate line, the common electrode, and the pixel
electrode included in the second substrate 262 and 283 may be
configured to be used as the touch sensor.
The foregoing has described the touch input device 1000 including
the touch sensor panel 100 capable of detecting whether or not the
touch has occurred and/or the touch position. The pressure sensor
440 according to the embodiment of the present invention is applied
to the aforementioned touch input device 1000, so that it is
possible to easily detect a magnitude of a touch pressure as well
as whether or not the touch has occurred and/or the touch position.
Hereinafter, described in detail is an example of a case of
detecting the touch pressure by applying the electrode sheet
according to the embodiment of the present invention to the touch
input device 1000. According to the embodiment, the touch input
device to which the pressure detection module is applied may not
have the touch sensor panel 100.
FIG. 3a is an exemplary cross sectional views of the pressure
sensor including a pressure electrode according to the embodiment
of the present invention. For example, the pressure sensor 440 may
include an electrode layer 441 between a first insulation layer 470
and a second insulation layer 471. The electrode layer 441 may
include a first electrode 450 and/or a second electrode 460. Here,
the first insulation layer 470 and the second insulation layer 471
may be made of an insulating material like polyimide. The first
electrode 450 and/or the second electrode 460 included in the
electrode layer 441 may include a material like copper. In
accordance with the manufacturing process of the pressure sensor
440, the electrode layer 441 and the second insulation layer 471
may be adhered to each other by means of an adhesive (not shown)
like an optically clear adhesive (OCA). Also, the pressure
electrodes 450 and 460 according to the embodiment may be formed by
positioning a mask, which has a through-hole corresponding to a
pressure electrode pattern, on the first insulation layer 470, and
then by spraying a conductive material.
FIG. 4a is a cross sectional view of the touch input device of a
first example, to which the pressure sensor and the pressure
detection module according to the embodiment of the present
invention can be applied.
The cross sectional view of the touch input device 1000 shown in
FIG. 4a may be a cross sectional view of a portion of the touch
input device 1000. As shown in FIG. 4a, the touch input device 1000
according to the embodiment of the present invention may include
the display panel 200A, a backlight unit 200B disposed under the
display panel 200A, and a cover layer 500 disposed on the display
panel 200A. In the touch input device 1000 according to the
embodiment, the pressure sensors 450 and 460 may be formed on a
cover 240. In this specification, the display panel 200A and the
backlight unit 200B are collectively referred to as a display
module 200. FIG. 4a shows that the pressure sensors 450 and 460 are
attached on the cover 240. However, according to the embodiment,
the pressure sensors 450 and 460 can be also attached to a
configuration which is included in the touch input device 1000 and
performs the same or similar function as/to that of the cover
240.
The touch input device 1000 according to the embodiment of the
present invention may include an electronic device including the
touch screen, for example, a cell phone, a personal data assistant
(PDA), a smart phone, a tablet personal computer, an MP3 player, a
laptop computer, etc.
At least a portion of the touch sensor is included within the
display panel 200A in the touch input device 1000 according to the
embodiment. Also, according to the embodiment, the drive electrode
and the receiving electrode which are for sensing the touch may be
included within the display panel 200A.
FIG. 4a does not show separately the touch sensor panel 100.
However, in the touch input device 1000 according to the first
example of the present invention, the lamination is made by an
adhesive like the optically clear adhesive (OCA) between the touch
sensor panel 100 and the display module 200 for detecting the touch
position. As a result, the display color clarity, visibility and
optical transmittance of the display module 200, which can be
recognized through the touch surface of the touch sensor panel 100,
can be improved. Here, the cover layer 500 may be disposed on the
touch sensor panel 100.
The cover layer 500 according to the embodiment may be comprised of
a cover glass which protects the front side of the display panel
200A and forms the touch surface. As shown in FIG. 4a, the cover
layer 500 may be formed wider than the display panel 200A.
Since the display panel 200A such as the LCD panel according to the
embodiment performs a function of only blocking or transmitting the
light without emitting light by itself, the backlight unit 200B may
be required. For example, the backlight unit 200B is disposed under
the display panel 200A, includes a light source and throws the
light on the display panel 200A, so that not only brightness and
darkness but also information having a variety of colors is
displayed on the screen. Since the display panel 200A is a passive
device, it is not self-luminous. Therefore, the rear side of the
display panel 200A requires a light source having a uniform
luminance distribution.
The backlight unit 200B according to the embodiment may include an
optical layer 220 for illuminating the display panel 200A. The
optical layer 220 will be described in detail with reference to
FIG. 4b.
The backlight unit 200B according to the embodiment may include the
cover 240. The cover 240 may be made of a metallic material. When a
pressure is applied from the outside through the cover layer 500 of
the touch input device 1000, the cover layer 500, the display
module 200, etc., may be bent. Here, the bending causes a distance
between the pressure sensor 450 and 460 and a reference potential
layer located within the display module to be changed. The
capacitance change caused by the distance change is detected
through the pressure sensors 450 and 460, so that the magnitude of
the pressure can be detected. Here, a pressure is applied to the
cover layer 500 in order to precisely detect the magnitude of the
pressure, the position of the pressure sensors 450 and 460 needs to
be fixed without changing. Therefore, the cover 240 is able to
perform a function of a support capable of fixing a pressure sensor
without being relatively bent even by the application of pressure.
According to the embodiment, the cover 240 is manufactured
separately from the backlight unit 200B, and may be assembled
together when the display module is manufactured.
In the touch input device 1000 according to the embodiment, a first
air gap 210 may be included between the display panel 200A and the
backlight unit 200B. This intends to protect the display panel 200A
and/or the backlight unit 200B from an external impact. This first
air gap 210 may be included in the backlight unit 200B.
The optical layer 220 and the cover 240, which are included in the
backlight unit 200B, may be configured to be spaced apart from each
other. A second air gap 230 may be provided between the optical
layer 220 and the cover 240. The second air gap 230 may be required
in order to ensure that the pressure sensors 450 and 460 disposed
on the cover 240 does not contact with the optical layer 220, and
in order to prevent that the optical layer 220 contacts with the
pressure sensors 450 and 460 and deteriorates the performance of
the optical layer 220 even though an external pressure is applied
to the cover layer 500 and the optical layer 220, the display panel
200A, and the cover layer 500 are bent.
The touch input device 1000 according to the embodiment may further
include supports 251 and 252 such that the display panel 200A, the
backlight unit 200B, and the cover layer 500 are coupled to
maintain a fixed shape. According to the embodiment, the cover 240
may be integrally formed with the support 251 and 252. According to
the embodiment, the support 251 and 252 may form a portion of the
backlight unit 200B.
The structure and function of the display panel 200A and the
backlight unit 200B is a publicly known art and will be briefly
described below. The backlight unit 200B may include several
optical parts.
FIG. 4b shows the optical layer 220 of the backlight unit 200B in
the touch input device according to the embodiment. FIG. 4b shows
the optical layer 220 when the LCD panel is used as the display
panel 200A.
In FIG. 4b, the optical layer 220 of the backlight unit 200B may
include a reflective sheet 221, a light guide plate 222, a diffuser
sheet 223, and a prism sheet 224. Here, the backlight unit 200B may
include a light source (not shown) which is formed in the form of a
linear light source or point light source and is disposed on the
rear and/or side of the light guide plate 222.
The light guide plate 222 may generally convert lights from the
light source (not shown) in the form of a linear light source or
point light source into light from a light source in the form of a
surface light source, and allow the light to proceed to the LCD
panel 200A.
A part of the light emitted from the light guide plate 222 may be
emitted to a side opposite to the LCD panel 200A and be lost. The
reflective sheet 221 may be positioned below the light guide plate
222 so as to cause the lost light to be incident again on the light
guide plate 222, and may be made of a material having a high
reflectance.
The diffuser sheet 223 functions to diffuse the light incident from
the light guide plate 222. For example, light scattered by the
pattern of the light guide plate 222 comes directly into the eyes
of the user, and thus, the pattern of the light guide plate 222 may
be shown as it is. Moreover, since such a pattern can be clearly
sensed even after the LCD panel 200A is mounted, the diffuser sheet
224 is able to perform a function to offset the pattern of the
light guide plate 222.
After the light passes through the diffuser sheet 223, the
luminance of the light is rapidly reduced. Therefore, the prism
sheet 224 may be included in order to improve the luminance of the
light by focusing the light again. The prism sheet 224 may include,
for example, a horizontal prism sheet and a vertical prism
sheet.
The backlight unit 200B according to the embodiment may include a
configuration different from the above-described configuration in
accordance with the technical change and development and/or the
embodiment. The backlight unit 200B may further include an
additional configuration as well as the foregoing configuration.
Also, in order to protect the optical configuration of the
backlight unit 200B from external impacts and contamination, etc.,
due to the introduction of the alien substance, the backlight unit
200B according to the embodiment may further include, for example,
a protection sheet on the prism sheet 224. The backlight unit 200B
may also further include a lamp cover in accordance with the
embodiment so as to minimize the optical loss of the light source.
The backlight unit 200B may also further include a frame which
maintains a shape enabling the light guide plate 222, the diffuser
sheet 223, the prism sheet 224, a lamp (not shown), and the like,
which are main components of the backlight unit 200B, to be exactly
combined together in accordance with an allowed dimension. Also,
the each of the configurations may be comprised of at least two
separate parts.
According to the embodiment, an additional air gap may be
positioned between the light guide plate 222 and the reflective
sheet 221. As a result, the lost light from the light guide plate
222 to the reflective sheet 221 can be incident again on the light
guide plate 222 by the reflective sheet 221. Here, between the
light guide plate 222 and the reflective sheet 221, for the purpose
of maintaining the additional air gap, the double-sided adhesive
tape (DAT) may be included on the edges of the light guide plate
222 and the reflective sheet 221.
As described above, the backlight unit 200B and the display module
including the backlight unit 200B may be configured to include in
itself the air gap such as the first air gap 210 and/or the second
air gap 230. Also, the air gap may be included between a plurality
of the layers included in the optical layer 220. Although the
foregoing has described that the LCD panel 200A is used, the air
gap may be included within the structure of another display
panel.
FIG. 4c is a cross sectional view of the touch input device of a
second example, to which the pressure sensor and pressure detection
module according to the embodiment of the present invention can be
applied. FIG. 4c shows a cross section of the touch input device
1000 that further includes a substrate 300 as well as the display
module 200. In the touch input device 1000 according to the
embodiment, the substrate 300, together with a second outermost
cover 320 of the touch input device 1000, functions as, for
example, a housing which surrounds a mounting space 310, etc.,
where the circuit board and/or battery for operation of the touch
input device 1000 are located. Here, the circuit board for
operation of the touch input device 1000 may be a main board. A
central processing unit (CPU), an application processor (AP) or the
like may be mounted on the circuit board. Due to the substrate 300,
the display module 200 is separated from the circuit board and/or
battery for operation of the touch input device 1000. Due to the
substrate 300, electrical noise generated from the display module
200 can be blocked. According to the embodiment, the substrate 300
may be referred to as a mid-frame in the touch input device
1000.
In the touch input device 1000, the cover layer 500 may be formed
wider than the display module 200, the substrate 300, and the
mounting space 310. As a result, the second cover 320 is formed in
such a manner as to surround the display module 200, the substrate
300, and the mounting space 310 where the circuit board is located.
Also, according to the embodiment, the pressure sensor 440 may be
included between the display module 200 and the substrate 300.
As with FIG. 4a, FIG. 4c does not show separately the touch sensor
panel 100. However, the touch input device 1000 according to the
embodiment of the present invention can detect the touch position
through the touch sensor panel 100. Also, according to the
embodiment, at least a portion of the touch sensor may be included
in the display panel 200A.
Here, the pressure sensor 440 may be attached to the substrate 300,
may be attached to the display module 200, or may be attached to
the display module 200 and the substrate 300.
As shown in FIGS. 4a and 4c, since the pressure sensor 440 in the
touch input device 1000 is disposed within the display module 200
or is disposed between the display module 200 and the substrate 300
and under the display module 200, the electrodes 450 and 460
included in the pressure sensor 440 can be made of not only a
transparent material but also an opaque material.
Hereafter, in the touch input device 1000 according to the
embodiment of the present invention, the principle and structure
for detecting the magnitude of touch pressure by using the pressure
sensor 440 will be described in detail. In FIGS. 5a to 5e, for
convenience of description, the electrodes 450 and 460 included in
the pressure sensor 440 are referred to as a pressure sensor.
FIGS. 5a and 5b show a relative distance between the reference
potential layer and the pressure sensor of the first example, which
are included in the touch input device, and show a pressure is
applied to the touch input device. In the touch input device 1000
according to the embodiment of the present invention, the pressure
sensors 450 and 460 may be attached on the cover 240 capable of
constituting the backlight unit 200B. In the touch input device
1000, the pressure sensors 450 and 460 and the reference potential
layer 600 may be spaced apart from each other by a distance
"d".
In FIG. 5a, the reference potential layer 600 and the pressure
sensor 450 and 460 may be spaced apart from each other with a
spacer layer (not shown) placed therebetween. Here, as described
with reference to FIGS. 4a and 4b, the spacer layer may be the
first air gap 210, the second air gap 230, and/or an additional air
gap which are included in the manufacture of the display module 200
and/or the backlight unit 200B. When the display module 200 and/or
the backlight unit 200A includes one air gap, the one air gap is
able to perform the function of the spacer layer. When the display
module 200 and/or the backlight unit 200A includes a plurality of
air gaps, the plurality of air gaps are able to collectively
perform the function of the spacer layer.
In the touch input device 1000 according to the embodiment, the
spacer layer may be located between the reference potential layer
600 and the pressure sensors 450 and 460. As a result, when a
pressure is applied to the cover layer 500, the reference potential
layer 600 is bent, so that a relative distance between the
reference potential layer 600 and the pressure sensors 450 and 460
may be reduced. The spacer layer may be implemented by the air
gap.
According to the embodiment, the spacer layer 420 may be made of an
impact absorbing material. Here, the impact absorbing material may
include sponge and a graphite layer. The spacer layer 420 may be
filled with a dielectric material in accordance with the
embodiment. The spacer layer 420 may be formed through a
combination of the air gap, the impact absorbing material, and the
dielectric material.
In the touch input device 1000 according to the embodiment, the
display module 200 may be bent or pressed by the touch applying the
pressure. The display module may be bent or pressed in such a
manner as to show the biggest transformation at the touch position.
When the display module is bent or pressed according to the
embodiment, a position showing the biggest transformation may not
match the touch position. However, the display module may be shown
to be bent or pressed at least at the touch position. For example,
when the touch position approaches close to the border, edge, etc.,
of the display module, the most bent or pressed position of the
display module may not match the touch position. The border or edge
of the display module may not be shown to be bent very little
depending on the touch.
Here, since the display module 200 in the touch input device 1000
according to the embodiment of the present invention may be bent or
pressed by the application of the pressure, the components (a
double-side adhesive tape, an adhesive tape 430, the supports 251
and 252, etc.) which are disposed at the border in order to
maintain the air gaps 210 and 310 and/or the spacer layer 420 may
be made of an inelastic material. That is, even though the
components which are disposed at the border in order to maintain
the air gaps 210 and 310 and/or the spacer layer 420 are not
compressed or pressed, the touch pressure can be detected by the
bending, etc., of the display module 200.
When the cover layer 500, the display panel 200A, and/or the back
light unit 200B are bent or pressed at the time of touching the
touch input device 1000 according to the embodiment, the cover 240
positioned below the spacer layer, as shown in FIG. 4b, may be less
bent or pressed due to the spacer layer. While FIG. 5b shows that
the cover 240 is not bent or pressed at all, this is just an
example. The lowest portion of the cover 240 to which the pressure
sensors 450 and 460 have been attached may be bent or pressed.
However, the degree to which the lowest portion of the cover 240 is
bent or pressed can be reduced by the spacer layer.
According to the embodiment, the spacer layer may be implemented in
the form of the air gap. The spacer layer may be made of an impact
absorbing material in accordance with the embodiment. The spacer
layer may be filled with a dielectric material in accordance with
the embodiment.
FIG. 5b shows that a pressure is applied to the structure of FIG.
5a. For example, when the external pressure is applied to the cover
layer 500 shown in FIG. 4a, it can be seen that a relative distance
between the reference potential layer 600 and the pressure sensors
450 and 460 is reduced from "d" to "d'". Accordingly, in the touch
input device 1000 according to the embodiment, when the external
pressure is applied, the reference potential layer 600 is
configured to be more bent than the cover 240 to which the pressure
sensors 450 and 460 have been attached, so that it is possible to
detect the magnitude of touch pressure.
FIGS. 4a, 5a, and 5b show that a first electrode 450 and a second
electrode 460 are included as the pressure sensors 450 and 460 for
detecting the pressure. Here, the mutual capacitance may be
generated between the first electrode 450 and the second electrode
460. Here, any one of the first and the second electrodes 450 and
460 may be a drive electrode and the other may be a receiving
electrode. A driving signal is applied to the drive electrode, and
a sensing signal may be obtained through the receiving electrode.
When voltage is applied, the mutual capacitance may be generated
between the first electrode 450 and the second electrode 460.
The reference potential layer 600 may have any potential which
causes the change of the mutual capacitance generated between the
first electrode 450 and the second electrode 460. For instance, the
reference potential layer 600 may be a ground layer having a ground
potential. The reference potential layer 600 may be any ground
layer which is included in the display module. According to the
embodiment, the reference potential layer 600 may be a ground
potential layer which is included in itself during the manufacture
of the touch input device 1000. For example, in the display panel
200A shown in FIGS. 2a to 2c, an electrode (not shown) for blocking
noise may be included between the first polarizer layer 271 and the
first substrate 261. This electrode for blocking the noise may be
composed of ITO and may function as the ground. Also, according to
the embodiment, a plurality of the common electrodes included in
the display panel 200A constitutes the reference potential layer
600. Here, the potential of the common electrode may be a reference
potential.
When a pressure is applied to the cover layer 500 by means of an
object, at least a portion of the display panel 200A and/or the
backlight unit 200B is bent, so that a relative distance between
the reference potential layer 600 and the first and second
electrodes 450 and 460 may be reduced from "d" to "d'". Here, the
less the distance between the reference potential layer 600 and the
first and second electrodes 450 and 460 is, the less the value of
the mutual capacitance between the first electrode 450 and the
second electrode 460 may be. This is because the distance between
the reference potential layer 600 and the first and second
electrodes 450 and 460 is reduced from "d" to "d'", so that a
fringing capacitance of the mutual capacitance is absorbed in the
reference potential layer 600 as well as in the object. When a
nonconductive object touches, the change of the mutual capacitance
is simply caused by only the change of the distance "d-d'" between
the reference potential layer 600 and the electrodes 450 and
460.
The foregoing has described that the pressure sensor 440 includes
the first electrode 450 and the second electrode 460 and the
pressure is detected by the change of the mutual capacitance
between the first electrode 450 and the second electrode 460. The
pressure sensor 440 may be configured to include only any one of
the first electrode 450 and the second electrode 460 (for example,
the first electrode 450).
FIGS. 5c and 5d show a relative distance between a reference
potential layer and a pressure sensor of a second example which are
included in the touch input device, and show that a pressure is
applied to the touch input device. Here, it is possible to detect
the magnitude of touch pressure by detecting the self-capacitance
between the first electrode 450 and the reference potential layer
600. Here, the change of the self-capacitance between the first
electrode 450 and the reference potential layer 600 is detected by
applying the driving signal to the first electrode 450 and by
receiving the reception signal from the first electrode 450, so
that the magnitude of the touch pressure is detected.
For example, the magnitude of the touch pressure can be detected by
the change of the capacitance between the first electrode 450 and
the reference potential layer 600, which is caused by the distance
change between the reference potential layer 600 and the first
electrode 450. Since the distance "d" is reduced with the increase
of the touch pressure, the capacitance between the reference
potential layer 600 and the first electrode 450 may be increased
with the increase of the touch pressure.
FIGS. 4a and 5a to 5d show that the first electrode 450 and/or the
second electrode 460 are relatively thick and they are directly
attached to the cover 240. However, this is just only for
convenience of description. In accordance with the embodiment, the
first electrode 450 and/or the second electrode 460 is the integral
sheet-type pressure sensor 440 may be attached to the cover 240 and
may have a relatively small thickness.
Although the foregoing has described that the pressure sensor 440
is attached to the cover 240 by referencing the touch input device
1000 shown in FIG. 4a, the pressure sensor 440 may be disposed
between the display module 200 and the substrate 300 in the touch
input device 1000 shown in FIG. 4c. According to the embodiment,
the pressure sensor 440 may be disposed under the display module
200. In this case, the reference potential layer 600 may be any
potential layer which is disposed on the substrate 300 or within
the display module 200. Also, according to the embodiment, the
pressure sensor 440 may be attached to the substrate 300. In this
case, the reference potential layer 600 may be any potential layer
which is disposed on or within the display module 200.
FIG. 5e shows the arrangement of pressure sensors of a third
example which is included in the touch input device. As shown in
FIG. 5e, the first electrode 450 may be disposed on the substrate
300, and the second electrode 460 may be disposed under the display
module 200. In this case, a separate reference potential layer may
not be required. When a pressure touch is performed on the touch
input device 1000, a distance between the display module 200 and
the substrate 300 may be changed, and thus, the mutual capacitance
between the first electrode 450 and the second electrode 460 may be
increased. Through the capacitance change, the magnitude of the
touch pressure can be detected. Here, the first electrode 450 and
the second electrode 460 may be included in the first pressure
sensor 440-1 and the second pressure sensor 440-2 respectively and
attached to the touch input device 1000.
The foregoing has described that the reference potential layer 600
is located apart from the components to which the pressure sensor
440 is attached in the touch input device 1000. It will be
described in FIGS. 6a to 6c that the component itself to which the
pressure sensor 440 is attached in the touch input device 1000
functions as the reference potential layer.
FIG. 6a is a cross sectional view showing a portion of the touch
input device to which the pressure sensor 440 has been attached
according to a first method. FIG. 6a shows that the pressure sensor
440 has been attached on the substrate 300, the display module 200,
or the cover 240.
As shown in FIG. 6b, the adhesive tape 430 having a predetermined
thickness may be formed along the border of the pressure sensor 440
so as to maintain the spacer layer 420. Though FIG. 6b shows that
the adhesive tape 430 is formed along the entire border (for
example, four sides of a quadrangle) of the pressure sensor 440,
the adhesive tape 430 may be formed only on at least a portion (for
example, three sides of a quadrangle) of the border of the pressure
sensor 440. Here, as shown in FIG. 6b, the adhesive tape 430 may
not be formed on an area including the electrodes 450 and 460. As a
result, when the pressure sensor 440 is attached to the substrate
300 or the display module 200 through the adhesive tape 430, the
pressure electrodes 450 and 460 may be spaced apart from the
substrate 300 or the display module 200 at a predetermined
distance. According to the embodiment, the adhesive tape 430 may be
formed on the top surface of the substrate 300, the bottom surface
of the display module 200, the surface of the cover 240. Also, the
adhesive tape 430 may be a double adhesive tape. FIG. 6b shows only
one of the pressure electrodes 450 and 460.
FIG. 6c is a partial cross sectional view of the touch input device
to which the pressure sensor has been attached according to a
second method. In FIG. 6c, after the pressure sensor 440 is placed
on the substrate 300, the display module 200, or the cover 240, the
pressure sensor 440 may be fixed to the substrate 300, the display
module 200, or the cover 240 by means of the adhesive tape 430. For
this, the adhesive tape 430 may come in contact with at least a
portion of the pressure sensor 440 and at least a portion of the
substrate 300, the display module 200, or the cover 240. FIG. 6c
shows that the adhesive tape 430 continues from the top of the
pressure sensor 440 to the exposed surface of the substrate 300,
the display module 200, or the cover 240. Here, only a portion of
the adhesive tape 430, which contacts with the pressure sensor 440,
may have adhesive strength. Therefore, in FIG. 6c, the top surface
of the adhesive tape 430 may not have the adhesive strength.
As shown in FIG. 6c, even if the pressure sensor 440 is fixed to
the substrate 300, the display module 200, or the cover 240 by
using the adhesive tape 430, a predetermined space, i.e., air gap
may be created between the pressure sensor 440 and the substrate
300, the display module 200, or the cover 240. This is because the
substrate 300, the display module 200, or the cover 240 is not
directly attached to the pressure sensor 440 by means of the
adhesive and because the pressure sensor 440 includes the pressure
electrodes 450 and 460 having a pattern, so that the surface of the
pressure sensor 440 may not be flat. The air gap of FIG. 6c may
also function as the spacer layer 420 for detecting the touch
pressure.
FIGS. 7a to 7e show pressure electrode patterns included in the
pressure sensor for pressure detection according to the embodiment
of the present invention. FIGS. 7a to 7c show the patterns of the
first electrode 450 and the second electrode 460 included in the
pressure sensor 440. The pressure sensor 440 including the pressure
electrode patterns shown in FIGS. 7a to 7c may be formed on the
cover 240, the substrate 300 or on the bottom surface of the
display module 200. The capacitance between the first electrode 450
and the second electrode 460 may be changed depending on a distance
between the reference potential layer 600 and the electrode layer
including both the first electrode 450 and the second electrode
460.
When the magnitude of the touch pressure is detected as the mutual
capacitance between the first electrode 450 and the second
electrode 460 is changed, it is necessary to form the patterns of
the first electrode 450 and the second electrode 460 so as to
generate the range of the capacitance required to improve the
detection accuracy. With the increase of a facing area or facing
length of the first electrode 450 and the second electrode 460, the
size of the capacitance that is generated may become larger.
Therefore, the pattern can be designed by adjusting the size of the
facing area, facing length and facing shape of the first electrode
450 and the second electrode 460 in accordance with the range of
the necessary capacitance. FIGS. 7b to 7c show that the first
electrode 450 and the second electrode 460 are formed in the same
layer, and show that the pressure electrode is formed such that the
facing length of the first electrode 450 and the second electrode
460 becomes relatively longer. The patterns of the pressure
electrodes 450 and 460 shown in FIGS. 7b to 7c can be used to
detect the pressure in the principle described in FIGS. 5a and
5c.
The electrode pattern shown in FIG. 7d can be used to detect the
pressure in the principle described in FIGS. 5c and 5d. Here, the
pressure electrode should not necessary have a comb teeth shape or
a trident shape, which is required to improve the detection
accuracy of the mutual capacitance change amount. The pressure
electrode may have, as shown in FIG. 7d, a plate shape (e.g.,
quadrangular plate).
The electrode pattern shown in FIG. 7e can be used to detect the
pressure in the principle described in FIG. 5e. Here, as shown in
FIG. 7e, the first electrode 450 and the second electrode 460 are
disposed orthogonal to each other, so that the capacitance change
amount detection sensitivity can be enhanced.
FIGS. 8a and 8b show a relation between a magnitude of a touch
pressure and a saturated area in the touch input device to which
the pressure sensor 440 has been applied according to the
embodiment of the present invention. Although FIGS. 8a and 8b show
that the pressure sensor 440 is attached to the substrate 300, the
following description can be applied in the same manner to a case
where the pressure sensor 440 is attached to the display module 200
or the cover 240.
The touch pressure with a sufficient magnitude makes a state where
the distance between the pressure sensor 440 and the substrate 300
cannot be reduced any more at a predetermined position. Hereafter,
the state is designated as a saturation state. For instance, as
shown in FIG. 8a, when the touch input device 1000 is pressed by a
force "f", the pressure sensor 440 contacts the substrate 300, and
thus, the distance between the pressure sensor 440 and the
substrate 300 cannot be reduced any more. Here, as shown on the
right of FIG. 8a, the contact area between the pressure sensor 440
and the substrate 300 may be indicated by "a".
However, in this case, when the magnitude of the touch pressure
becomes larger, the contact area between the pressure sensor 440
and the substrate 300 in the saturation state where the distance
between the pressure sensor 440 and the substrate 300 cannot be
reduced any more may become greater. For example, as shown in FIG.
8b, when the touch input device 1000 is pressed by a force "F"
greater than the force "f", the contact area between the pressure
sensor 440 and the substrate 300 may become greater. As shown on
the right of FIG. 8a, the contact area between the pressure sensor
440 and the substrate 300 may be indicated by "A". As such, the
greater the contact area, the more the mutual capacitance between
the first electrode 450 and the second electrode 460 may be
reduced. Hereafter, it will be described that the magnitude of the
touch pressure is calculated by the change of the capacitance
according to the distance change. This may include that the
magnitude of the touch pressure is calculated by the change of the
saturation area in the saturation state.
FIGS. 8a and 8b are described with reference to the example shown
in FIG. 6a. It is apparent that the description with reference to
FIGS. 8a and 8b can be applied in the same manner to the examples
described with reference to FIGS. 4a, 4c, 5a to 5e, and 6c. More
specifically, the magnitude of the touch pressure can be calculated
by the change of the saturation area in the saturation state where
the distance between the pressure sensor 440 and either the ground
layer or the reference potential layer 600 cannot be reduced any
more.
The top surface of the substrate 300 may also have the ground
potential in order to block the noise. FIG. 9 shows the cross
sections of the pressure sensor according to the embodiment of the
present invention. Referring to (a) of FIG. 9, a cross section when
the pressure sensor 440 including the pressure electrodes 450 and
460 is attached to the substrate 300 or the display module 200 is
shown. Here, in the pressure sensor 440, since the pressure
electrodes 450 and 460 are disposed between the first insulation
layer 470 and the second insulation layer 471, a short-circuit can
be prevented from occurring between the pressure electrodes 450 and
460 and either the substrate 300 or the display module 200. Also,
depending on the kind and/or implementation method of the touch
input device 1000, the substrate 300 or the display module 200 on
which the pressure electrodes 450 and 460 are attached may not have
the ground potential or may have a weak ground potential. In this
case, the touch input device 1000 according to the embodiment of
the present may further include a ground electrode (not shown)
between the first insulation layer 470 and either the substrate 300
or the display module 200. According to the embodiment, another
insulation layer (not shown) may be included between the ground
electrode and either the substrate 300 or the display module 200.
Here, the ground electrode (not shown) is able to prevent the size
of the capacitance generated between the first electrode 450 and
the second electrode 460, which are pressure electrodes, from
increasing excessively.
Cross sections of a portion of the pressure sensor attached to the
touch input device in accordance with the embodiment of the present
invention are shown in (a) to (d) of FIG. 9.
For example, when the first electrode 450 and the second electrode
460 included in the pressures sensor 440 are formed in the same
layer, the pressure sensor 440 may be configured as shown in (a) of
FIG. 9. Here, each of the first electrode 450 and the second
electrode 460 shown in (a) of FIG. 9 may be, as shown in FIG. 13a,
composed of a plurality of lozenge-shaped electrodes. Here, the
plurality of the first electrodes 450 are connected to each other
in a first axial direction, and the plurality of the second
electrodes 460 are connected to each other in a second axial
direction orthogonal to the first axial direction. The
lozenge-shaped electrodes of at least one of the first and the
second electrodes 450 and 460 are connected to each other through a
bridge, so that the first electrode 450 and the second electrode
460 may be insulated from each other. Also, the first electrode 450
and the second electrode 460 shown in (a) of FIG. 9 may be composed
of an electrode having a form shown in FIG. 13b.
In the pressure sensor 440, it can be considered that the first
electrode 450 and the second electrode 460 are formed in different
layers in accordance with the embodiment and form the electrode
layer. A cross section when the first electrode 450 and the second
electrode 460 are formed in different layers is shown in (b) of
FIG. 9. As shown in (b) of FIG. 9, the first electrode 450 may be
formed on the first insulation layer 470, and the second electrode
460 may be formed on the second insulation layer 471 positioned on
the first electrode 450. According to the embodiment, the second
electrode 460 may be covered with a third insulation layer 472. In
other words, the pressure sensor 440 may include the first to the
third insulation layers 470 to 472, the first electrode 450, and
the second electrode 460. Here, since the first electrode 450 and
the second electrode 460 are disposed in different layers, they can
be implemented so as to overlap each other. For example, the first
electrode 450 and the second electrode 460 may be, as shown in FIG.
13c, formed similarly to the pattern of the drive electrode TX and
receiving electrode RX which are arranged in the form of M.times.N
array. Here, M and N may be natural numbers greater than 1. Also,
as shown in FIG. 13a, the lozenge-shaped first and the second
electrodes 450 and 460 may be disposed in different layers
respectively.
A cross section when the pressure sensor 440 is formed to include
only the first electrode 450 is shown in (c) of FIG. 9. As shown in
(c) of FIG. 9, the pressure sensor 440 including the first
electrode 450 may be disposed on the substrate 300 or on the
display module 200. For example, the first electrode 450 may be
disposed as shown in FIG. 12d.
A cross section when the first pressure sensor 440-1 including the
first electrode 450 is attached to the substrate 300 and the second
pressure sensor 440-2 including the second electrode 460 is
attached to the display module 200 is shown in (d) of FIG. 9. As
shown in (d) of FIG. 9, the first pressure sensor 440-1 including
the first electrode 450 may be disposed on the substrate 300. Also,
the second pressure sensor 440-2 including the second electrode 460
may be disposed on the bottom surface of the display module
200.
As with the description related to (a) of FIG. 9, when substrate
300, the display module 200, or the cover 240 on which the pressure
sensors 450 and 460 are attached may not have the ground potential
or may have a weak ground potential, the pressure sensor 440 may
further include, as shown in (a) to (d) of FIG. 9, a ground
electrode (not shown) under the first insulation layers 470, 470-1,
and 470-2 disposed to contact the substrate 300, the display module
200, or the cover 240. Here, the pressure sensor 440 may further
include an additional insulation layer (not shown) which is
opposite to the first insulation layers 470, 470-1, and 470-2 such
that the ground electrode (not shown) is located between the
additional insulation layer and the first insulation layers 470,
470-1, and 470-2.
The foregoing has described the case where the touch pressure is
applied to the top surface of the touch input device 1000. However,
even when the touch pressure is applied to the bottom surface of
the touch input device 1000, the pressure sensor 440 is able to
detect the touch pressure in the same manner.
As shown in FIGS. 4 to 9, in the case where the pressure sensor 440
according to the embodiment of the present invention is attached to
the touch input device, when a pressure is applied to the touch
input device by the object 500, the display module 200 or the
substrate 300 is bent or pressed, so that the magnitude of the
touch pressure can be calculated. Here, for the purpose of
describing the change of the distance between the reference
potential layer 600 and the pressure sensor 440, FIGS. 4 to 9 show
that the display module 200, the substrate 300, or only a portion
of the display module 200 to which the pressure is directly applied
by the object 500 is bent or pressed. However, the member to which
the pressure is not directly applied by the object 500 is also
actually bent or pressed. However, since how much the member to
which the pressure is directly applied is bent or pressed is more
than how much the member to which the pressure is not directly
applied is bent or pressed, the descriptions of FIGS. 4 to 9 are
possible. As such, when the pressure is applied to the touch input
device, the pressure sensor 440 attached to the touch input device
may be also bent or pressed. Here, when the pressure applied to the
touch input device is released, the display module 200 or the
substrate 300 is restored to its original state, and thus, the
pressure sensor 440 attached to the touch input device should also
maintain its original shape. Also, when the original shape of the
pressure sensor 440 is difficult to maintain, there may be
difficulties in the process of attaching the pressure sensor 440 to
the touch input device. Therefore, it is recommended that the
pressure sensor 440 should have a rigidity to maintain its original
shape.
When the pressure electrodes 450 and 460 included in the pressure
sensor 440 are made of soft conductive metal such as Al, Ag, and
Cu, the pressure electrodes 450 and 460 have a low rigidity and a
thickness of only several micrometers. Therefore, the original
shape of the pressure sensor 440 is difficult to maintain only by
the pressure electrodes 450 and 460. Accordingly, it is recommended
that the first insulation layer 470 or the second insulation layer
471 which is disposed on or under the pressure electrodes 450 and
460 has a rigidity enough to maintain the original shape of the
pressure sensor 440.
Specifically, as shown in FIG. 3b, the pressure sensor 440 may
include the electrode layer and support layers 470b and 471b. Here,
the electrode layer may be composed of the pressure electrodes 450
and 460 including the first electrode 450 and the second electrode
460. In this case, the pressure sensor 440 may be used to detect
the change of the capacitance between the first electrode 450 and
the second electrode 460, which is changed according to a relative
distance change between the electrode layer and the reference
potential layer 600 which is disposed apart from the pressure
sensor 440. Also, the electrode layer may be composed of the
pressure electrodes 450 and 460 including only one electrode. In
this case, the pressure sensor 440 may be used to detect the
capacitance change between the electrode layer and the reference
potential layer 600, which is changed according to the relative
distance change between the electrode layer and the reference
potential layer 600 which is disposed apart from the pressure
sensor 440.
Here, when the reference potential layer 600 which is disposed
apart from the pressure sensor 440 does not have a uniform
reference potential according to each input position, or when the
distance change between the reference potential layer and the
electrode layer is not uniform for the pressure having the same
magnitude in accordance with the input position, for example, when
the surface of the reference potential layer 600 which is disposed
apart from the pressure sensor 440 is not uniform, it may be
difficult to use the capacitance change amount between the
electrode layer and the reference potential layer 600 which is
disposed apart from the pressure sensor 440. As shown in FIG. 3h,
the pressure sensor 440 according to the embodiment of the present
invention may include a first electrode layer including the first
electrode 450 and include a second electrode layer which includes
the second electrode 460 and is disposed apart from the first
electrode layer. In this case, the pressure sensor 440 may be used
to detect the capacitance change between the first electrode layer
and the second electrode layer, which is changed according to a
relative distance change between the first electrode layer and the
second electrode layer. Here, any one of the first electrode layer
and the second electrode layer may be the reference potential
layer. As such, the capacitance change between the electrode layers
is detected, which is changed according to the distance change
between the electrode layers located within the pressure sensor
440, so that it is possible to detect a uniform capacitance change
even when, as described above, the uniform capacitance change
cannot be detected from the reference potential layer located
outside the pressure sensor 440. Here, an elastic layer 480 which
has a restoring force and absorbs the impact may be further
included between the first electrode layer and the second electrode
layer in order to provide uniformity of the distance change between
the first electrode layer and the second electrode layer. Also, as
shown in (d) of FIG. 9, the pressure sensor 440 may include the
first pressure sensor including the first electrode layer and a
first support layer and the second pressure sensor including the
second electrode layer and a second support layer. In this case,
the pressure sensor 440 may be used to detect the capacitance
change between the first electrode layer and the second electrode
layer, which is changed according to the relative distance change
between the first electrode layer and the second electrode
layer.
The support layers 470b and 471b may be made of a material, for
example, a resin material, highly rigid metal, paper, or the like,
which has a rigidity capable of maintaining the shape of the
pressure sensor 440 even when the distance change occurs between
the pressure sensor 440 and the reference potential layer 600.
The pressure sensor 440 may further include the first insulation
layer 470 and the second insulation layer 471. Here, the electrode
layer may be located between the first insulation layer 470 and the
second insulation layer 471, and the support layers 470b and 471b
may be included in at least any one of the first insulation layer
470 and the second insulation layer 471.
The first insulation layer 470 or the second insulation layer 471
may further include electrode covering layers 470a and 471a. The
electrode covering layers 470a and 471a may function to insulate
the electrode layer and may function to protect the electrode
layer, for example, to prevent the electrode from being oxidized,
scraped, cracked, or the like. Also, the electrode covering layers
470a and 471a are formed of or coated with a material with a color,
thereby preventing the electrode sheet 440 from being degraded due
to exposure to the sun during the distribution of the electrode
sheet 440. Here, the electrode covering layers 470a and 471a may be
adhered to the electrode layer or to the support layers 470b and
471b by means of an adhesive or may be printed or coated on the
support layers 470b and 471b. The electrode covering layers 470a
and 471a may be also made of a highly rigid resin material.
However, since the thickness of the electrode covering layer is
only several micrometers, it is difficult to maintain the original
shape of the pressure sensor 440 of about 100 .mu.m.
Also, as shown in FIGS. 3e and 3f, the pressure sensor 440
according to the embodiment of the present invention may further
include the adhesive layer 430 and a protective layer 435 outside
either the first insulation layer 470 or the second insulation
layer 471. Though it has been described in FIGS. 4 to 9 that the
adhesive layer 430 is formed separately from the pressure sensor
440, the adhesive layer 430 may be manufactured as one component
included in the pressure sensor 440. The protective layer 435
functions to protect the adhesive layer 430 before the pressure
sensor 440 is attached to the touch input device. When the pressure
sensor 440 is attached to the touch input device, the protective
layer 435 is removed and the pressure sensor 440 can be attached to
the touch input device by using the adhesive layer 430.
As shown in FIG. 3c, the electrode covering layers 470a and 471a
may not be formed on the side where the support layers 470b and
471b are formed. The support layers 470b and 471b made of a resin
material, paper, or the like are able to insulate and protect the
electrode layer. In this case, likewise, the support layers 470b
and 471b may be formed of or coated with a material with a
color.
As shown in FIG. 3d, any one of the first insulation layer 470 and
the second insulation layer 471 may have a thickness less than that
of the other. Specifically, since the capacitance (C) is inversely
proportional to the distance "d" between the electrode layer and
the reference potential layer 600, FIG. 3i shows that, for the same
distance change, the smaller the distance between the electrode
layer and the reference potential layer 600 is, the greater the
capacitance change amount becomes, and then it becomes easier to
precisely detect the pressure. Therefore, the pressure sensor 440
is attached to the touch input device including the cover 240, the
substrate 300 and/or the display module 200, and the thickness of
one of the first and second insulation layers 470 and 471, which is
closer to the reference potential layer 600 than the other, may be
less than that of the other.
Preferably, only one of the first and second insulation layers 470
and 471 may include the support layers 470b and 471b. Specifically,
in the state where the pressure sensor 440 is attached to the touch
input device, only one of the first and second insulation layers
470 and 471, which is farther from the reference potential layer
600 than the other, may include the support layers 470b and
471b.
Likewise, as shown in (d) of FIG. 9, when the first pressure sensor
440-1 is attached to the substrate 300 and the second pressure
sensor 440-2 is attached to the display module 200, the thickness
of the second insulation layer 471-1 which is closer to the second
electrode 460 out of the first and the second insulation layers
470-1 and 471-1 may be less than the thickness of the first
insulation layer 470-1, the thickness of the fourth insulation
layer 471-2 which is closer to the first electrode 450 out of the
third and the fourth insulation layers 470-2 and 471-2 may be less
than the thickness of the third insulation layer 470-2. Preferably,
only the first and the third insulation layers 470-1 and 470-2 may
include the support layer 470b.
As shown in FIG. 3h, even when the pressure sensor 440 includes the
first electrode layer including the first electrode 450 and the
second electrode layer which includes the second electrode 460 and
is disposed apart from the first electrode layer, the thickness of
any one of the first insulation layer 470 and the second insulation
layer 471 may be less than that of the other. Specifically, in a
case where the pressure sensor 440 is attached to the display
module 200 or the substrate 300, when a pressure is applied to the
touch input device, a distance between the pressure sensor 440 and
the member to which the pressure sensor 440 has been attached is
not changed. However, a distance between the pressure sensor 440
and the member to which the pressure sensor 440 has been not
attached is changed. Here, the capacitance change according to the
distance change between the pressure sensor 440 and the reference
potential layer 600 located outside the pressure sensor 440 is not
desired. Thus, it is preferable to minimize such a capacitance
change. Therefore, the pressure sensor 440 is attached to the touch
input device including the substrate 300 and the display module 200
in such a manner as to be attached to any one of a side of the
substrate 300, which is opposite to the display module 200 and a
side of the display module 200, which is opposite to the substrate
300. In a state where the pressure sensor 440 is attached to the
touch input device, the thickness of one of the first and second
insulation layers 470 and 471, which is closer to the side to which
the pressure sensor 440 has been attached than the other, may be
less than that of the other.
Preferably, only one of the first and second insulation layers 470
and 471 may include the support layers 470b and 471b. Specifically,
in the state where the pressure sensor 440 is attached to the touch
input device, only one of the first and second insulation layers
470 and 471, which is farther from the side to which the pressure
sensor 440 has been attached than the other, may include the
support layers 470b and 471b.
The pressure sensor 440 shown in FIG. 3e is attached to the cover
240, the substrate 300 or the display module 200 toward the side on
which the adhesive layer 430 is formed. The pressure sensor 440
shown in FIG. 3e is used to detect the magnitude of the pressure
according to the distance change between the electrode layer and
the reference potential layer 600 formed in or on the member to
which the pressure sensor 440 has not been attached. The pressure
sensor 440 shown in FIG. 3f is attached to the cover 240, the
substrate 300 or the display module 200 toward the side on which
the adhesive layer 430 is formed. The pressure sensor 440 shown in
FIG. 3f is used to detect the magnitude of the pressure according
to the distance change between the electrode layer and the
reference potential layer 600 formed in or on the member to which
the pressure sensor 440 has been attached.
A space in which the pressure sensor 440 is disposed, for example,
an interval between the display module 200 and the substrate 300
depends on the touch input device and is about 100 to 500 .mu.m.
The thicknesses of the pressure sensor 440 and the support layers
470b and 471b are limited according to the interval. As shown in
FIG. 3g, when the pressure sensor is attached to the display module
200 and a distance between the display module 200 and the substrate
300 is 500 .mu.m, it is desirable that the pressure sensor 440 has
a thickness of 50 .mu.m to 450 .mu.m. If the thickness of the
pressure sensor 440 is less than 50 .mu.m, the thickness of the
support layers 470b and 471b having a relatively high rigidity also
becomes smaller, so that the original shape of the pressure sensor
440 is difficult to maintain. If the thickness of the pressure
sensor 440 is larger than 450 .mu.m, an interval between the
pressure sensor 440 and the substrate 300, i.e., the reference
potential layer, is significantly reduced below 50 .mu.m, so that
it is difficult to measure the pressure with a wide range.
The pressure sensor 440 is disposed in the touch input device.
Therefore, as with the touch input device, the pressure sensor 440
is required to meet a given reliability under a predetermined
condition, for example, temperature, humidity, etc. In order to
meet the reliability that the appearance and characteristics are
less changed under a harsh condition of 85 to -40.degree. C., a
humidity condition of 85%, etc., it is desirable that the support
layers 470b and 471b are made of a resin material. Specifically,
the support layers 470b and 471b may be formed of polyimide (PI) or
polyethylene terephthalate (PET). Also, polyethylene terephthalate
costs less than polyimide. The material constituting the support
layers 470b and 471b may be determined in terms of cost and
reliability.
As described above, in order to detect the pressure through the
touch input device 1000 to which the pressure sensor 440 is applied
according to the embodiment of the present invention, it is
necessary to sense the capacitance change occurring in the pressure
electrodes 450 and 460. Therefore, it is necessary for the driving
signal to be applied to the drive electrode out of the first and
second electrodes 450 and 460, and it is required to detect the
touch pressure by the capacitance change amount by obtaining the
sensing signal from the receiving electrode. According to the
embodiment, it is possible to additionally include a pressure
detection device in the form of a pressure sensing IC for the
operation of the pressure detection. The pressure detection module
(not shown) according to the embodiment of the present invention
may include not only the pressure sensor 440 for pressure detection
but also the pressure detection device.
In this case, the touch input device repeatedly has a configuration
similar to the configuration of FIG. 1 including the drive unit
120, the sensing unit 110, and the controller 130, so that the area
and volume of the touch input device 1000 increase.
According to the embodiment, the touch detection device 1000 may
apply the driving signal for pressure detection to the pressure
sensor 440 by using the touch detection device for the operation of
the touch sensor panel 100, and may detect the touch pressure by
receiving the sensing signal from the pressure sensor 440.
Hereafter, the following description will be provided by assuming
that the first electrode 450 is the drive electrode and the second
electrode 460 is the receiving electrode.
For this, in the touch input device 1000 to which the pressure
sensor 440 is applied according to the embodiment of the present
invention, the driving signal may be applied to the first electrode
450 from the drive unit 120, and the second electrode 460 may
transmit the sensing signal to the sensing unit 110. The controller
130 may perform the scanning of the touch sensor panel 100, and
simultaneously perform the scanning of the touch pressure
detection, or the controller 130 performs the time-sharing, and
then may generate a control signal such that the scanning of the
touch sensor panel 100 is performed in a first time interval and
the scanning of the pressure detection is performed in a second
time interval different from the first time interval.
Therefore, in the embodiment of the present invention, the first
electrode 450 and the second electrode 460 should be electrically
connected to the drive unit 120 and/or the sensing unit 110. Here,
it is common that the touch detection device for the touch sensor
panel 100 corresponds to the touch sensing IC 150 and is formed on
one end of the touch sensor panel 100 or on the same plane with the
touch sensor panel 100. The pressure electrode 450 and 460 included
in the pressure sensor 440 may be electrically connected to the
touch detection device of the touch sensor panel 100 by any method.
For example, the pressure electrode 450 and 460 may be connected to
the touch detection device through a connector by using the second
PCB 210 included in the display module 200. For example, conductive
traces 461 which electrically extend from the first electrode 450
and the second electrode 460 respectively may be electrically
connected to the touch sensing IC 150 through the second PCB 210,
etc.
FIGS. 10a to 10b show that the pressure sensor 440 including the
pressure electrodes 450 and 460 is attached to the bottom surface
of the display module 200. FIGS. 10a and 10b show the second PCB
210 on which a circuit for the operation of the display panel has
been mounted is disposed on a portion of the bottom surface of the
display module 200.
FIG. 10a shows that the pressure sensor 440 is attached to the
bottom surface of the display module 200 such that the first
electrode 450 and the second electrode 460 are connected to one end
of the second PCB 210 of the display module 200. Here, the first
electrode 450 and the second electrode 460 may be connected to the
one end of the second PCB 210 by using a double conductive tape.
Specifically, since the thickness of the pressure sensor 440 and an
interval between the substrate 300 and the display module 200 where
the pressure sensor 440 is disposed are very small, the thickness
can be effectively reduced by connecting both the first electrode
450 and the second electrode 460 to the one end of the second PCB
210 by using the double conductive tape rather than by using a
separate connector. A conductive pattern may be printed on the
second PCB 210 in such a manner as to electrically connect the
pressure electrodes 450 and 460 to a necessary component like the
touch sensing IC 150, etc. The detailed description of this will be
provided with reference to FIGS. 11a to 11c. An attachment method
of the pressure sensor 440 including the pressure electrodes 450
and 460 shown in FIG. 10a can be applied in the same manner to the
substrate 300 and the cover 240.
FIG. 10b shows that the pressure sensor 440 including the first
electrode 450 and the second electrode 460 is not separately
manufactured but is integrally formed on the second PCB 210 of the
display module 200. For example, when the second PCB 210 of the
display module 200 is manufactured, a certain area is separated
from the second PCB, and then not only the circuit for the
operation of the display panel but also the pattern corresponding
to the first electrode 450 and the second electrode 460 can be
printed on the area. A conductive pattern may be printed on the
second PCB 210 in such a manner as to electrically connect the
first electrode 450 and the second electrode 460 to a necessary
component like the touch sensing IC 150, etc.
FIGS. 11a to 11c show a method for connecting the pressure
electrodes 450 and 460 included in the pressure sensor 440 to the
touch sensing IC 150. In FIGS. 11a to 11c, the touch sensor panel
100 is included outside the display module 200. FIGS. 12a to 12c
show that the touch detection device of the touch sensor panel 100
is integrated in the touch sensing IC 150 mounted on the first PCB
160 for the touch sensor panel 100.
FIG. 11a shows that the pressure electrodes 450 and 460 included in
the pressure sensor 440 attached to the display module 200 are
connected to the touch sensing IC 150 through a first connector
121. As shown in FIG. 11a, in a mobile communication device such as
a smart phone, the touch sensing IC 150 is connected to the second
PCB 210 for the display module 200 through the first connector 121.
The second PCB 210 may be electrically connected to the main board
through a second connector 224. Therefore, through the first
connector 121 and the second connector 224, the touch sensing IC
150 may transmit and receive a signal to and from the CPU or AP for
the operation of the touch input device 1000.
Here, while FIG. 11a shows that the pressure sensor 440 is attached
to the display module 200 by the method shown in FIG. 10b, the
first electrode 450 can be attached to the display module 200 by
the method shown in FIG. 10a. A conductive pattern may be printed
on the second PCB 210 in such a manner as to electrically connect
the first electrode 450 and the second electrode 460 to the touch
sensing IC 150 through the first connector 121.
FIG. 11b shows that the pressure electrodes 450 and 460 included in
the pressure sensor 440 attached to the display module 200 are
connected to the touch sensing IC 150 through a third connector
473. In FIG. 11b, the pressure electrodes 450 and 460 may be
connected to the main board for the operation of the touch input
device 1000 through the third connector 473, and in the future, may
be connected to the touch sensing IC 150 through the second
connector 224 and the first connector 121. Here, the pressure
electrodes 450 and 460 may be printed on the additional PCB
separated from the second PCB 210. Otherwise, according to the
embodiment, the pressure electrodes 450 and 460 may be attached to
the touch input device 1000 in the form of the pressure sensor 440
shown in FIGS. 3a to 3h and may be connected to the main board
through the connector 473 by extending the conductive trace, etc.,
from the pressure electrodes 450 and 460.
FIG. 11c shows that the pressure electrodes 450 and 460 are
directly connected to the touch sensing IC 150 through a fourth
connector 474. In FIG. 11c, the pressure electrodes 450 and 460 may
be connected to the first PCB 160 through the fourth connector 474.
A conductive pattern may be printed on the first PCB 160 in such a
manner as to electrically connect the fourth connector 474 to the
touch sensing IC 150. As a result, the pressure electrodes 450 and
460 may be connected to the touch sensing IC 150 through the fourth
connector 474. Here, the pressure electrodes 450 and 460 may be
printed on the additional PCB separated from the second PCB 210.
The second PCB 210 may be insulated from the additional PCB so as
not to be short-circuited with each other. Also, according to the
embodiment, the pressure electrodes 450 and 460 may be attached to
the touch input device 1000 in the form of the pressure sensor 440
shown in FIGS. 3a to 3h and may be connected to the first PCB 160
through the connector 474 by extending the conductive trace, etc.,
from the pressure electrodes 450 and 460.
The connection method of FIGS. 11b and 11c can be applied to the
case where the pressure sensor 440 including the pressure electrode
450 and 460 is formed on the substrate 300 or on the cover 240 as
well as on the bottom surface of the display module 200.
FIGS. 11a to 11c have been described by assuming that a chip on
board (COB) structure in which the touch sensing IC 150 is formed
on the first PCB 160. However, this is just an example. The present
invention can be applied to the chip on board (COB) structure in
which the touch sensing IC 150 is mounted on the main board within
the mounting space 310 of the touch input device 1000. It will be
apparent to those skilled in the art from the descriptions of FIGS.
11a to 11c that the connection of the pressure electrodes 450 and
460 through the connector can be also applied to another
embodiment.
The foregoing has described the pressure electrodes 450 and 460,
that is to say, has described that the first electrode 450
constitutes one channel as the drive electrode and the second
electrode 460 constitutes one channel as the receiving electrode.
However, this is just an example. According to the embodiment, the
drive electrode and the receiving electrode constitute a plurality
of channels respectively. Here, a high-pressure detection accuracy
of the touch can be obtained by the plurality of channels
constituted by the drive electrode and the receiving electrode, and
it is possible to detect multi pressure of a multi touch.
FIGS. 12a to 12d show that the pressure electrode of the present
invention constitutes the plurality of channels. FIG. 12a shows
that first electrodes 450-1 and 450-2 and second electrodes 460-1
and 460-2 constitute two channels respectively. FIG. 12a shows that
all of the first electrodes 450-1 and 450-2 and the second
electrodes 460-1 and 460-2 which constitute the two channels are
included in one pressure sensor 440. FIG. 12b shows that the first
electrode 450 constitutes two channels 450-1 and 450-2 and the
second electrode 460 constitutes one channel FIG. 12c shows the
first electrode 450-1 to 450-5 constitute five channels and the
second electrode 460-1 and 460-5 constitute five channels. Even in
this case, all of the electrodes constituting the five channels may
be also included in one pressure sensor 440. FIG. 12d shows that
first electrodes 451 to 459 constitute nine channels and all of the
first electrodes 451 to 459 are included in one pressure sensor
440.
As shown in FIGS. 12a to 12d and 13a to 13d, when the plurality of
channels are formed, a conductive pattern which is electrically
connected to the touch sensing IC 150 from each of the first
electrode 450 and/or the second electrode 460 may be formed.
Here, described is a case in which the plurality of channels shown
in FIG. 12d are constituted. In this case, since a plurality of
conductive patterns 461 should be connected to the first connector
121 with a limited width, a width of the conductive pattern 461 and
an interval between the adjacent conductive patterns 461 should be
small. Polyimide is more suitable for a fine process of forming the
conductive pattern 461 with such a small width and interval than
polyethylene terephthalate. Specifically, the support layers 470b
and 471b of the pressure sensor 440, in which the conductive
pattern 461 is formed, may be made of polyimide. Also, a soldering
process may be required to connect the conductive pattern 461 to
the first connector 121. For a soldering process which is performed
at a temperature higher than 300.degree. C., polyimide resistant to
heat is more suitable than polyethylene terephthalate relatively
vulnerable to heat. Here, for the purpose of reducing production
costs, a portion of the support layers 470b and 471b, in which the
conductive pattern 461 is not formed, may be made of polyethylene
terephthalate, and a portion of the support layers 470b and 471b,
in which the conductive pattern 461 is formed, may be made of
polyimide.
FIGS. 12a to 12d and 13a to 13d show that the pressure electrode
constitutes a single or a plurality of channels. The pressure
electrode may be comprised of a single or a plurality of channels
by a variety of methods. While FIGS. 12a to 12d and 13a to 13d do
not show that the pressure electrodes 450 and 460 are electrically
connected to the touch sensing IC 150, the pressure electrodes 450
and 460 can be connected to the touch sensing IC 150 by the method
shown in FIGS. 11a to 11c and other methods.
In the foregoing description, the first connector 121 or the fourth
connector 474 may be a double conductive tape. Specifically, since
the first connector 121 or the fourth connector 474 may be disposed
at a very small interval, the thickness can be effectively reduced
by using the double conductive tape rather than a separate
connector. Also, according to the embodiment, the functions of the
first connector 121 and the fourth connector 474 can be implemented
by a Flex-on-Flex Bonding (FOF) method capable of achieving a small
thickness.
Hereinafter, various methods in which the pressure sensor 440
detects the magnitude of the pressure of the touch on the basis of
the capacitance change amount detected from the channel.
Example of First Method
FIG. 20a is a flowchart for describing an example of a method for
detecting the magnitude of the touch pressure by using a plurality
of channels in the touch input device according to the embodiment
of the present invention.
When a pressure is applied to the touch surface (S10), the
magnitude of the touch pressure is detected based on the sum of
values obtained by multiplying the change amounts of the
capacitances detected in the respective channels and SNR
improvement scaling factors assigned to the respective channels
(S20). For example, the magnitude of the touch pressure can be
calculated based on the sum of values obtained by multiplying the
change amounts of the capacitances detected in the respective
fifteen first electrodes 450 in the pressure sensor 440 shown in
FIG. 13d and the SNR improvement scaling factors assigned to the
respective channels. As such, by using a sum of values obtained by
multiplying the pressure magnitudes detected from the respective
channels (or the capacitance values corresponding thereto) and SNR
improvement scaling factors assigned to the respective channels, or
by using an average value of the sum, the accuracy of the pressure
magnitude detected by using the plurality of channels can be
further improved than the accuracy of the pressure magnitude
detected by using a single channel.
Example of Second Method
FIG. 14a is a view showing that a pressure is applied to a
predetermined position in the pressure sensor shown in FIG. 13d.
FIG. 14b is a cross sectional view showing a form in which the
touch input device is bent when the touch pressure is applied to a
touch surface corresponding to a position "A" of FIG. 14a. FIG. 14c
is a cross sectional view showing a form in which the touch input
device is bent when the touch pressure is applied to a touch
surface corresponding to a position "C" of FIG. 14a.
When the touch pressure is applied to the touch surface
corresponding to a position "A" shown in FIG. 14a, that is, when
the touch pressure is applied to the central portion of the display
module 200, the degree of bending of the display module 200 may be
relatively high as shown in FIG. 14b. On the other hand, when the
touch pressure is applied to the touch surface corresponding to a
position "B" shown in FIG. 14a, that is, when the touch pressure is
applied to the edge of the display module 200, the degree of
bending of the display module 200 may be relatively small as shown
in FIG. 14c. Specifically, as shown in FIGS. 14b and 14c, when the
same touch pressure is applied, the distance d1 between the
pressure electrode 450 and the position where the display module
200 is most bent when the touch pressure is applied to the central
portion of the display module 200 may be smaller than the distance
d2 between the pressure electrode 450 and the position where the
display module 200 is most bent when the touch pressure is applied
to the edge of the display module 200. Therefore, even though the
same touch pressure is applied, the capacitance change amounts
detected in the respective channels are different according to the
position where the touch pressure is applied. Therefore, there is a
requirement for a method capable of detecting a more accurate
pressure value than the pressure value detected by using the sum or
average of values obtained by multiplying the pressure magnitudes
detected from the respective channels or the capacitances
corresponding to the pressure magnitudes by the SNR improvement
scaling factors assigned to the respective channels.
FIG. 20b is a flowchart for describing another example of a method
for detecting the magnitude of the touch pressure by using a
plurality of channels in the touch input device according to the
embodiment of the present invention. FIG. 15 is a view showing a
sensitivity correction scaling factor assigned to each first
electrode in the pressure sensor shown in FIG. 13d.
When a pressure is applied to the touch surface (S100), the
magnitude of the touch pressure is detected based on the sum of
values obtained by multiplying the change amounts of the
capacitances detected in the respective channels, the sensitivity
correction scaling factors assigned previously to the respective
channels, and the SNR improvement scaling factor assigned to the
respective channels (S200). For example, as shown in FIG. 15, the
sensitivity correction scaling factor of 1 is assigned to the first
electrode 450 located at the central portion of the display module
200, a scaling factor of 6 is assigned to the first electrodes 450
adjacent to the first electrode 450 located at the central portion,
and sensitivity correction scaling factors of 12 and 16 are
respectively assigned to the first electrodes 450 located at the
edge. As described above, when a smaller sensitivity correction
scaling factor is assigned to the channel corresponding to the
central portion of the display module 200 and a larger sensitivity
correction scaling factor is assigned to the channel corresponding
to the edge of the display module 200, the central portion of the
display module 200 is, as shown in FIGS. 14b and 14c, bent more
than the edge of the display module 200 when the same pressure is
applied. Therefore, it is possible to offset that the change amount
of the capacitance detected at the central portion of the display
module 200 becomes greater than the change amount of the
capacitance detected at the edge of the display module 200. As a
result, a more accurate pressure value can be calculated.
Example of Third Method
FIG. 16a is a graph for describing, when the pressure is applied to
the position shown in FIG. 14a, a relation between a volume change
amount of the touch input device and the magnitude of the applied
pressure. FIG. 16b is a cross sectional view showing the volume
change amount of the touch input device shown in FIG. 14b. FIG. 16c
is a cross sectional view showing the volume change amount of the
touch input device shown in FIG. 14c.
When the same touch pressure is applied, a volume (hereinafter,
referred to as volume change amount) at which the touch input
device 1000 is deformed when the touch pressure is applied to the
central portion of the display module 200 may be greater than the
volume change amount of the touch input device 1000 when the touch
pressure is applied to the edge of the display module 200. In other
words, when the same touch pressure is applied to the touch surface
corresponding to the positions "A", "B", and "C" shown in FIG. 14a,
as shown in FIGS. 16a to 16c, the volume change amount of the touch
input device 1000 when the touch pressure is applied to the
position "A", the central portion of the display module 200, is
greater than the volume change amount of the touch input device
1000 when the touch pressure is applied the position "C" located at
the edge relative to the position "A" of the display module
200.
Here, when the touch pressure is applied to the same position, the
magnitude of the applied pressure and the volume change amount of
the touch input device 1000 have a linear relationship. In other
words, when the touch pressures having different magnitudes are
applied to any one of the positions "A", "B", and "C" shown in FIG.
14a, the volume change amount of the touch input device 1000 is, as
shown in FIG. 16a, changed in proportion to the magnitude of the
applied pressure.
Therefore, the magnitude of the pressure can be detected by
estimating the volume change amount of the touch input device
1000.
First, when a pressure having a predetermined magnitude is applied
to a predetermined touch position of the display module 200, a
reference value corresponding to the touch position is stored in a
memory (not shown) on the basis of the capacitance detected from
each channel. In this case, the reference value may be the volume
change amount of the touch input device 1000 calculated based on
the capacitance detected from each channel. Alternatively, the
reference value may be a normalized pressure value having a linear
relationship with the volume change amount of the touch input
device 1000, or may be a slope in the graph shown in FIG. 16a. Such
a method is repeatedly performed for each touch position, and the
reference value for all positions of the entire area of the display
module 200 when a pressure having a predetermined magnitude is
applied is stored in the memory. Here, since it is difficult to
generate the reference value for all positions of the entire area
of the display module 200, the reference value may be generated and
stored only for a plurality of representative positions spaced
apart by a predetermined interval. For example, the volume change
amounts of 432 calculated based on each capacitance change amount
detected when a pressure of 800 g is applied to each of the touch
positions of 432 (18.times.24) spaced apart at regular intervals of
the display module 200 may be stored in the memory.
Next, a method for detecting the magnitude of the touch pressure by
using the reference value is shown.
FIG. 20c is a flowchart for describing further another example of a
method for detecting the magnitude of the touch pressure by using a
plurality of channels in the touch input device according to the
embodiment of the present invention. FIG. 17a is a partial
perspective view for describing a form in which the touch input
device is deformed when the pressure is applied to the touch input
device. FIG. 17b is a view for describing the estimation of the
volume change amount of the touch input device when the pressure is
applied to the touch input device. FIG. 17c is a cross sectional
view of FIG. 17b.
When a pressure is applied to the touch surface (S1000), the touch
position is detected (S2000), and a distance change corresponding
to each channel is calculated from the change amount of the
capacitance detected in each channel (S3000).
The value of capacitance detected in each channel depends on the
configuration of the pressure electrode or the configuration of the
circuit for sensing the touch pressure. However, when the touch
pressure is applied, the value of capacitance can be represented by
a function of the distance change "di" corresponding to each
channel shown in FIG. 17c. Therefore, it is possible to calculate
the distance change "di" corresponding to each channel by
performing an inverse calculation on the capacitance value detected
from each channel. Here, the distance change "di" corresponding to
each channel means a distance which corresponds to each channel and
at which the surface of the touch input device is deformed after
the pressure is applied with respect to the time before the
pressure is applied.
FIG. 18a shows an equivalent circuit of a device for sensing a
pressure capacitance 11 between the first electrode 450 and the
second electrode 460 when, as shown in FIGS. 13a to 13c, the first
electrode 450 is composed of the drive electrode TX and the second
electrode 460 is composed of the receiving electrode RX, so that
the magnitude of the touch pressure is detected from the change of
the mutual capacitance between the first electrode 450 and the
second electrode 460. Here, a relational expression between the
driving signal Vs and the output signal Vo can be expressed by the
following equation (1).
.times..times. ##EQU00001##
Here, among the capacitance between the first electrode 450 and the
second electrode 460, the capacitance which is lost as a reference
potential layer is fringing capacitance. Here, the pressure
capacitance 11 can be expressed as follows.
C.sub.p=C.sub.0+C.sub.fringing=C.sub.0+.alpha.f(d) Equation (2)
Here, Co is a fixed capacitance value generated between the first
electrode 450 and the second electrode 460, and C.sub.fringing is a
capacitance value generated by fringing effect between the first
electrode 450 and the second electrode 460. The equation (2)
represents the value of C.sub.fringing by the distance "d" and a
coefficient ".alpha.". The fixed capacitance means a capacitance
generated by the first electrode 450 and the second electrode 460
irrespective of the distance "d" between the reference potential
layer and the electrode.
When a random pressure is applied to any position of the display
module 200, the distance change "di" corresponding to each channel
can be calculated by performing an inverse calculation on the
capacitance change amounts detected in each of the channels, the
equation (1), and the equation (2).
FIG. 18b shows an equivalent circuit of a device for sensing the
capacitance 11 between the first electrode 450 and the reference
potential layer when, as shown in FIG. 13d, the driving signal is
applied to the first electrode 450 and the reception signal is
detected from the first electrode 450, so that the magnitude of the
touch pressure is detected from the change of the self-capacitance
of the first electrode 450.
When a first switch 21 is turned on, the pressure capacitor 11 is
charged to a power supply voltage VDD to which one end of the first
switch 21 is connected. When a third switch 23 is turned on
immediately after the first switch 21 is turned off, the electric
charges charged in the pressure capacitor 11 are transferred to an
amplifier 31 to obtain the output signal Vo corresponding thereto.
When a second switch 22 is turned on, all the electric charges
remaining in the pressure capacitor 11 are discharged. When the
third switch 23 is turned on immediately after the second switch 22
is turned off, the electric charges are transferred to the pressure
capacitor 11 through a feedback capacitor 32 to obtain the output
signal corresponding thereto. Here, the output signal Vo of the
circuit shown in the figure can be expressed by the following
equation (3).
.times..times..times..times..times. ##EQU00002##
Here, .epsilon. is a dielectric constant
.epsilon..sub.0.epsilon..sub.r of the material filled between the
first electrode 450 and the reference potential layer, and "A" is
the area of the first electrode 450.
When a random pressure is applied to any position of the display
module 200, the distance change "di" corresponding to each channel
can be calculated by performing an inverse calculation on the
capacitance change amounts detected in each of the channels and the
equation (3).
The volume change amount of the touch input device is estimated by
using the calculated distance change "di" corresponding to each
channel (S4000). Specifically, when the touch pressure is applied,
the surface of the touch input device 1000 is deformed as shown in
FIG. 17a, and the volume change amount of the touch input device
1000 due to the deformation of the surface of the touch input
device 1000 can be estimated as the sum of the volume change
amounts corresponding to the respective channels shown in FIGS. 17b
and 17c. Here, when the areas corresponding to the respective
channels are the same, for example, when the areas of the first
electrodes 450 shown in FIG. 13d are the same, the sum of the
volume change amounts corresponding to the respective channels may
be a value obtained by multiplying the sum of the distance changes
"di" corresponding to the respective channels by by the area "A" of
the first one electrode 450.
Here, when the touch pressure is applied to a predetermined
position, the magnitude of the applied pressure and the volume
change amount of the touch input device 1000 have, as shown in FIG.
16a, a linear relationship. Therefore, the magnitude of the applied
pressure is calculated on the basis of the estimated volume change
amount of the touch input device 1000, the SNR improvement scaling
factors assigned to the respective channels, and the reference
value which is stored in the memory and corresponds to the touch
position (S5000).
For example, on the assumption that the SNR improvement scaling
factors assigned to the respective channels are all 1, when the
estimated volume change amount of the touch input device 1000 is
1000 and the volume change amount stored in the memory as a
reference value corresponding to the touch position for a pressure
of 800 g is 2000, the magnitude of the applied pressure is 400
g.
Also, when the reference value corresponding to the input touch
position is not stored in the memory, the pressure value can be
calculated through various interpolations such as linear
interpolation, bi-cubic interpolation, etc., by using the reference
value which is stored in the memory and corresponds to a touch
position adjacent to the input touch position.
FIG. 19a is a view for describing a case where a pressure is
applied to a position of the pressure sensor shown in FIG. 14a,
which corresponds to a position "D" of FIG. 19a. FIG. 19b is a
graph for describing the calculation of the pressure value when the
pressure is applied to the position "D" shown in FIG. 19a.
For example, when reference values corresponding to the position
"A" and the position "B" shown in FIG. 19a are stored in the memory
and when a reference value corresponding to the position "D" which
is a mid-point between the position "A" and the position "B" is not
stored in the memory, the reference value of the position "D" can
be, as shown in FIG. 19b, estimated by linearly interpolating the
reference values of the position "A" and the position "B", that is
to say, by taking an intermediate value between the reference value
of the position "A" and the reference value of the position "B".
The magnitude of the pressure applied to the position "D" can be
calculated by using the estimated reference value of the position
"D".
As described above, by calculating the magnitude of the pressure on
the basis of the volume change amount by the touch pressure, it is
possible to detect a more accurate pressure magnitude. The accurate
magnitude of the pressure can be detected even though the reference
potential layer or the pressure sensor is deformed from its initial
position.
Hereinafter, a method for calculating the SNR improvement scaling
factor will be described.
FIG. 21a is a graph showing an amplitude of a signal including
information on the capacitance detected in the channel
corresponding to the position "a" of FIG. 17c. FIG. 21b is a graph
showing an amplitude of a signal including information on the
capacitance detected in the channel corresponding to the position
"b" of FIG. 17c.
As shown in FIG. 17c, when a touch pressure is applied to the
central portion of the display module, the amplitude of the signal
including information on the capacitance detected in the channel
corresponding to the position "a" may be greater than the amplitude
of the signal including information on the capacitance detected in
the channel corresponding to the position "b". Here, the
capacitance detected in each channel may be changed by various
factors such as the change in an electric field or a magnetic field
around the touch input device 1000, temperature variation, and the
like, as well as the pressure applied to the touch input device
1000. The capacitance change due to the factors other than the
pressure applied to the touch input device 1000 corresponds to
noise to be removed in the detection of the magnitude of the
pressure. As shown in FIGS. 21a and 21b, the signal including
information on the capacitance detected in each channel is detected
in a form in which a signal due to the applied pressure and a
signal due to noise are combined. Here, as shown in FIG. 21a, a
proportion occupied by the amplitude of the signal due to the
pressure among the signals detected at the position "a"
corresponding to the central portion of the display module, that is
to say, the position to which the pressure has been applied,
occupies is larger than a proportion occupied by the amplitude of
the signal due to noise. On the other hand, as shown in FIG. 21b, a
proportion occupied by the amplitude of the signal due to the
pressure among the signals detected at the position "b"
corresponding to the edge of the display module, which is far from
the position to which the pressure has been applied, is relatively
less than a proportion occupied by the amplitude of the signal due
to noise. Here, since the amplitude of the signal due to noise is
generally constant irrespective of the position to which the
pressure has been applied, the amplitude of the signal due to noise
detected in each channels is generally constant. However, since the
amplitude of the signal due to the pressure is different depending
on the position to which the pressure has been applied, the
amplitude of the signal due to the pressure detected in each
channel is different depending on the position to which the
pressure has been applied.
Therefore, in the detection of the pressure magnitude, by excluding
a signal which is detected in a channel where the amplitude of the
signal due to noise is relatively larger than the amplitude of the
signal due to the pressure, or by reducing how much the signal
contributes to the detection of the magnitude of the pressure, how
much the amplitude of the signal due to noise is reduced is higher
than how much the amplitude of the signal due to the pressure is
reduced. Therefore, overall SNR can be improved. Specifically,
overall SNR at the time of detecting the pressure can be improved
by assigning an appropriate SNR improvement scaling factor to each
channel.
Here, the position to which the pressure has been applied and the
position where the display module shows the largest deformation do
not necessarily match each other. However, generally, the display
module is more greatly deformed at the position to which the
pressure has been applied than other positions. Therefore, the
amplitude of the signal including information on the capacitance
detected in the channel corresponding to the position to which the
pressure has been applied is generally greater than the amplitude
of the signal including information on the capacitance detected in
the channel corresponding to the other positions. Therefore, the
SNR improvement scaling factor which is assigned to each channel
can be calculated according to the amplitude of the signal
including information on the capacitance detected at the position
to which the pressure has been applied, i.e., the touch position or
detected in each channel.
FIGS. 22a and 22b are views for describing the SNR improvement
scaling factor which is assigned to each channel when a pressure is
applied to a position "P". FIG. 22c is a view showing capacitance
change amounts detected in the respective channels when the
pressure is applied to the position "P".
First, a method for calculating the SNR improvement scaling factor
on the basis of the amplitude of the signal including information
on the capacitance detected in each channel will be described.
The SNR improvement scaling factor of 1 may be assigned to N number
of the channels in which the signal with the largest amplitude is
detected among the signals detected in the respective channels, and
the SNR improvement scaling factor of 0 may be assigned to the
remaining channels. In this case, the pressure is detected by using
only some channels in which the signal with a large amplitude is
detected among the total channels, and SNR can be improved by
excluding the channel in which the signal with a small amplitude in
detecting the pressure. Here, N is a natural number equal to or
greater than 1 and equal to or smaller than the total number of the
channels. Specifically, when a pressure is applied to the position
"P" of FIG. 22a and N is four, the SNR improvement scaling factor
of 1 is assigned to the channels CH2, CH4, CH5, and CH8 of FIG. 22c
in which the four signals with the largest amplitude are detected,
and the SNR improvement scaling factor of 0 is assigned to the
remaining channels. Here, by applying the SNR improvement scaling
factor to the above-described example of the first method, the
magnitude of the pressure can be detected by using 310 that is a
sum of the capacitance change amounts detected in CH2, CH4, CH5,
and CH8. Also, the SNR improvement scaling factor of 1 may be
assigned to a channel in which a signal with an amplitude equal to
or greater than a predetermined ratio of the amplitude of the
signal with the largest amplitude among the signals detected in the
respective channels is detected, and the SNR improvement scaling
factor of 0 may be assigned to the remaining channels. In this case
as well, the pressure is detected by using only some channels in
which the signal with a large amplitude is detected among the total
channels, and SNR can be improved by excluding the channel in which
the signal with a small amplitude in detecting the pressure.
Specifically, when a pressure is applied to the position "P" of
FIG. 22a and the predetermined ratio is 50%, the SNR improvement
scaling factor of 1 is assigned to the channels CH4, CH5, and CH8
shown in FIG. 22c, in which a signal with an amplitude equal to or
greater than 55 that is 50% of the amplitude of the signal output
from the channel CH5 in which the signal with the largest amplitude
is detected is detected. The SNR improvement scaling factor of 0 is
assigned to the remaining channels. Here, by applying the SNR
improvement scaling factor to the above-described example of the
first method, the magnitude of the pressure can be detected by
using 260 that is a sum of the capacitance change amounts detected
in CH4, CH5, and CH8.
Also, a method for calculating the SNR improvement scaling factor
on the basis of the touch position will be described.
The SNR improvement scaling factor of 1 may be assigned to N number
of the channels which are the closest to the touch position, and
the SNR improvement scaling factor of 0 may be assigned to the
remaining channels. In this case, the amplitude of the signal
detected in the channel close to the touch position is generally
greater than the amplitude of the signal detected in the channel
relatively far from the touch position. Therefore, the pressure is
detected by using only some channels in which the signal with a
large amplitude is detected among the total channels, and SNR can
be improved by excluding the channel in which the signal with a
small amplitude in detecting the pressure. Here, N is a natural
number equal to or greater than 1 and equal to or smaller than the
total number of the channels. Specifically, when a pressure is
applied to the position "P" of FIG. 22a and N is four, the SNR
improvement scaling factor of 1 is assigned to the channels CH4,
CH5, CH7, and CH8 of FIG. 22c, which are the closest to the touch
position, and the SNR improvement scaling factor of 0 is assigned
to the remaining channels. Here, by applying the SNR improvement
scaling factor to the above-described example of the first method,
the magnitude of the pressure can be detected by using 305 that is
a sum of the capacitance change amounts detected in CH4, CH5, CH7,
and CH8.
Also, the SNR improvement scaling factor of 1 is assigned to the
channel located within a predetermined distance from the touch
position, and the SNR improvement scaling factor of 0 is assigned
to the remaining channels. In this case as well, the pressure is
detected by using only some channels in which the signal with a
large amplitude is detected among the total channels, and SNR can
be improved by excluding the channel in which the signal with a
small amplitude in detecting the pressure. Specifically, when a
pressure is applied to the position "P" of FIG. 22a and the
predetermined distance is "r" shown in FIG. 22a, the SNR
improvement scaling factor of 1 is assigned to the channels CH1,
CH2, CH4, CH5, CH6, CH7, and CH8 which are, as shown in FIG. 22c,
located within the distance "r", and the SNR improvement scaling
factor of 0 is assigned to the remaining channels. Here, by
applying the SNR improvement scaling factor to the above-described
example of the first method, the magnitude of the pressure can be
detected by using 385 that is a sum of the capacitance change
amounts detected in CH1, CH2, CH4, CH5, CH6, CH7, and CH8.
Also, the SNR improvement scaling factor which is assigned to each
channel can be calculated based on a distance between the touch
position and each channel. For example, the distance between the
touch position and each channel may be inversely proportional to
the SNR improvement scaling factor which is assigned to each
channel. Here, SNR can be improved by reducing how much the signal
with a small amplitude among the total channels contributes to the
detection of the pressure. Specifically, when a pressure is applied
to the position "P" of FIG. 22b and a distance between the touch
position and the channel j is "dj", the SNR improvement scaling
factor proportional to "1/dj" may be assigned to the channel j. For
example, when "d1" to "d15" shown in FIG. 22b have values of 15,
13.5, 13.3, 11.3, 9.3, 8.8, 8.5, 5.3, 4.5, 7.3, 3.3, 1, 8.5, 5.3,
and 4.5, "1/dj"s of 0.067, 0.074, 0.075, 0.088, 0.108, 0.114,
0.118, 0.189, 0.122, 0.137, 0.303, 1, 0.118, 0.189, and 0.222 are
assigned as the SNR improvement scaling factor to CH1 to CH15
respectively. By applying the SNR improvement scaling factor to the
above-described example of the first method, the magnitude of the
pressure can be detected by using a sum of values obtained by
multiplying the capacitance change amounts detected in the
respective channels by the SNR improvement scaling factor.
The foregoing has described the example of applying the SNR
improvement scaling factor to the above-described example of the
first method. Additionally, it is possible to detect the magnitude
of the pressure by applying the SNR improvement scaling factor to
the example of the second method or the third method in the same
manner.
Although the pressure sensor 440 having the type shown in FIG. 13d
has been described above, the embodiment of the present invention
is not limited to this. The embodiment of the present invention can
be applied to a pressure sensor including the pressure electrode
having the types shown in FIGS. 13a to 13c.
When the pressure sensor 440 is configured to form a plurality of
channels, multi pressure of a multi touch can be detected. This can
be performed, for example, by using the pressure magnitudes
obtained from the channels of the pressure electrodes 450 and 460
disposed at a position corresponding to each of the multiple touch
positions obtained from the touch sensor panel 100. Alternatively,
when the pressure sensor 440 is configured to form a plurality of
channels, the touch position can be directly detected by the
pressure sensor 440, and multi pressure can be also detected by
using the pressure magnitudes obtained from the channels of the
pressure electrodes 450 and 460 disposed at the corresponding
position.
Although embodiments of the present invention were described above,
these are just examples and do not limit the present invention.
Further, the present invention may be changed and modified in
various ways, without departing from the essential features of the
present invention, by those skilled in the art. For example, the
components described in detail in the embodiments of the present
invention may be modified. Further, differences due to the
modification and application should be construed as being included
in the scope and spirit of the present invention, which is
described in the accompanying claims.
REFERENCE NUMERALS
TABLE-US-00001 1000: touch input device 100: touch sensor panel
120: drive unit 110: sensing unit 130: controller 200: display
module 300: substrate 400: pressure detection module 420: spacer
layer 440: pressure sensor 450, 460: electrode 470: first
insulation layer 471: second insulation layer 470a, 471a: electrode
covering layer 470b, 471b: support layer 430: adhesive layer 435:
protective layer 480: elastic layer
* * * * *